version 3.0.1
Copyright © 2004 - 2017 The SCons Foundation
2004 - 2017
Table of Contents
Glob
Decider
FunctionDecider
Function$CPPPATH
Construction VariableDepends
FunctionParseDepends
FunctionIgnore
FunctionRequires
FunctionAlwaysBuild
FunctionConstruction Environment
: the Environment
FunctionConstruction Environment
Construction Environment
: the subst
MethodConstruction Environment
: the DefaultEnvironment
FunctionConstruction Environments
Construction Environments
: the Clone
MethodReplace
MethodSetDefault
MethodAppend
MethodAppendUnique
MethodPrepend
MethodPrependUnique
MethodSCONSFLAGS
Environment VariableGetOption
FunctionSetOption
FunctionAddOption
Functionvariable
=value
Build VariablesUnknownVariables
FunctionInstall
BuilderCopy
FactoryDelete
FactoryMove
FactoryTouch
FactoryMkdir
FactoryChmod
FactoryExecute
FunctionSConscript
CallVariantDir
FunctionVariantDir
With an SConscript
FileGlob
with VariantDir
Construction Environment
Generator
Emitter
Command
BuilderConfigure Contexts
typedef
EnsurePythonVersion
FunctionEnsureSConsVersion
FunctionSConscript
Files: the Exit
FunctionFindFile
FunctionFlatten
FunctionGetLaunchDir
Function--debug=explain
OptionDump
Method--tree
Option--debug=presub
Option--debug=findlibs
Option--debug=stacktrace
Option--taskmastertrace
Option--debug=prepare
OptionList of Examples
Thank you for taking the time to read about SCons. SCons is a next-generation software construction tool, or make tool--that is, a software utility for building software (or other files) and keeping built software up-to-date whenever the underlying input files change.
The most distinctive thing about SCons is that its configuration files are actually scripts, written in the Python programming language. This is in contrast to most alternative build tools, which typically invent a new language to configure the build. SCons still has a learning curve, of course, because you have to know what functions to call to set up your build properly, but the underlying syntax used should be familiar to anyone who has ever looked at a Python script.
Paradoxically, using Python as the configuration file format makes SCons easier for non-programmers to learn than the cryptic languages of other build tools, which are usually invented by programmers for other programmers. This is in no small part due to the consistency and readability that are hallmarks of Python. It just so happens that making a real, live scripting language the basis for the configuration files makes it a snap for more accomplished programmers to do more complicated things with builds, as necessary.
There are a few overriding principles we try to live up to in designing and implementing SCons:
First and foremost, by default, SCons guarantees a correct build even if it means sacrificing performance a little. We strive to guarantee the build is correct regardless of how the software being built is structured, how it may have been written, or how unusual the tools are that build it.
Given that the build is correct, we try to make SCons build software as quickly as possible. In particular, wherever we may have needed to slow down the default SCons behavior to guarantee a correct build, we also try to make it easy to speed up SCons through optimization options that let you trade off guaranteed correctness in all end cases for a speedier build in the usual cases.
SCons tries to do as much for you out of the box as reasonable, including detecting the right tools on your system and using them correctly to build the software.
In a nutshell, we try hard to make SCons just "do the right thing" and build software correctly, with a minimum of hassles.
One word of warning as you read through this Guide: Like too much Open Source software out there, the SCons documentation isn't always kept up-to-date with the available features. In other words, there's a lot that SCons can do that isn't yet covered in this User's Guide. (Come to think of it, that also describes a lot of proprietary software, doesn't it?)
Although this User's Guide isn't as complete as we'd like it to be, our development process does emphasize making sure that the SCons man page is kept up-to-date with new features. So if you're trying to figure out how to do something that SCons supports but can't find enough (or any) information here, it would be worth your while to look at the man page to see if the information is covered there. And if you do, maybe you'd even consider contributing a section to the User's Guide so the next person looking for that information won't have to go through the same thing...?
SCons would not exist without a lot of help from a lot of people, many of whom may not even be aware that they helped or served as inspiration. So in no particular order, and at the risk of leaving out someone:
First and foremost, SCons owes a tremendous debt to Bob Sidebotham, the original author of the classic Perl-based Cons tool which Bob first released to the world back around 1996. Bob's work on Cons classic provided the underlying architecture and model of specifying a build configuration using a real scripting language. My real-world experience working on Cons informed many of the design decisions in SCons, including the improved parallel build support, making Builder objects easily definable by users, and separating the build engine from the wrapping interface.
Greg Wilson was instrumental in getting SCons started as a real project when he initiated the Software Carpentry design competition in February 2000. Without that nudge, marrying the advantages of the Cons classic architecture with the readability of Python might have just stayed no more than a nice idea.
The entire SCons team have been absolutely wonderful to work with, and SCons would be nowhere near as useful a tool without the energy, enthusiasm and time people have contributed over the past few years. The "core team" of Chad Austin, Anthony Roach, Bill Deegan, Charles Crain, Steve Leblanc, Greg Noel, Gary Oberbrunner, Greg Spencer and Christoph Wiedemann have been great about reviewing my (and other) changes and catching problems before they get in the code base. Of particular technical note: Anthony's outstanding and innovative work on the tasking engine has given SCons a vastly superior parallel build model; Charles has been the master of the crucial Node infrastructure; Christoph's work on the Configure infrastructure has added crucial Autoconf-like functionality; and Greg has provided excellent support for Microsoft Visual Studio.
Special thanks to David Snopek for contributing his underlying "Autoscons" code that formed the basis of Christoph's work with the Configure functionality. David was extremely generous in making this code available to SCons, given that he initially released it under the GPL and SCons is released under a less-restrictive MIT-style license.
Thanks to Peter Miller for his splendid change management system, Aegis, which has provided the SCons project with a robust development methodology from day one, and which showed me how you could integrate incremental regression tests into a practical development cycle (years before eXtreme Programming arrived on the scene).
And last, thanks to Guido van Rossum for his elegant scripting language, which is the basis not only for the SCons implementation, but for the interface itself.
The best way to contact people involved with SCons, including the author, is through the SCons mailing lists.
If you want to ask general questions about how to use SCons
send email to scons-users@scons.org
.
If you want to contact the SCons development community directly,
send email to scons-dev@scons.org
.
If you want to receive announcements about SCons,
join the low-volume announce@scons.tigris.org
mailing list.
This chapter will take you through the basic steps of installing SCons on your system, and building SCons if you don't have a pre-built package available (or simply prefer the flexibility of building it yourself). Before that, however, this chapter will also describe the basic steps involved in installing Python on your system, in case that is necessary. Fortunately, both SCons and Python are very easy to install on almost any system, and Python already comes installed on many systems.
Because SCons is written in Python,
you must obviously have Python installed on your system
to use SCons.
Before you try to install Python,
you should check to see if Python is already
available on your system by typing
python -V
(capital 'V')
or
python --version
at your system's command-line prompt.
$ python -V
Python 2.5.1
And on a Windows system with Python installed:
C:\>python -V
Python 2.5.1
If Python is not installed on your system, you will see an error message stating something like "command not found" (on UNIX or Linux) or "'python' is not recognized as an internal or external command, operable progam or batch file" (on Windows). In that case, you need to install Python before you can install SCons.
The standard location for information about downloading and installing Python is http://www.python.org/download/. See that page for information about how to download and install Python on your system.
SCons will work with any 2.x version of Python from 2.7 on; 3.0 and later are not yet supported. If you need to install Python and have a choice, we recommend using the most recent 2.x Python version available. Newer Pythons have significant improvements that help speed up the performance of SCons.
SCons comes pre-packaged for installation on a number of systems, including Linux and Windows systems. You do not need to read this entire section, you should need to read only the section appropriate to the type of system you're running on.
SCons comes in RPM (Red Hat Package Manager) format, pre-built and ready to install on Red Hat Linux, Fedora, or any other Linux distribution that uses RPM. Your distribution may already have an SCons RPM built specifically for it; many do, including SUSE, Mandrake and Fedora. You can check for the availability of an SCons RPM on your distribution's download servers, or by consulting an RPM search site like http://www.rpmfind.net/ or http://rpm.pbone.net/.
If your distribution supports installation via yum, you should be able to install SCons by running:
# yum install scons
If your Linux distribution does not already have
a specific SCons RPM file,
you can download and install from the
generic RPM provided by the SCons project.
This will install the
SCons script(s) in /usr/bin
,
and the SCons library modules in
/usr/lib/scons
.
To install from the command line, simply download the
appropriate .rpm
file,
and then run:
# rpm -Uvh scons-3.0.1-1.noarch.rpm
Or, you can use a graphical RPM package manager. See your package manager application's documentation for specific instructions about how to use it to install a downloaded RPM.
Debian Linux systems use a different package management format that also makes it very easy to install SCons.
If your system is connected to the Internet, you can install the latest official Debian package by running:
# apt-get install scons
SCons provides a Windows installer
that makes installation extremely easy.
Download the scons-3.0.1.win32.exe
file from the SCons download page at
http://scons.org/pages/download.html.
Then all you need to do is execute the file
(usually by clicking on its icon in Windows Explorer).
These will take you through a small
sequence of windows that will install
SCons on your system.
If a pre-built SCons package is not available for your system,
then you can still easily build and install SCons using the native
Python distutils
package.
The first step is to download either the
scons-3.0.1.tar.gz
or scons-3.0.1.zip
,
which are available from the SCons download page at
http://www.scons.org/download.html.
Unpack the archive you downloaded,
using a utility like tar
on Linux or UNIX,
or WinZip on Windows.
This will create a directory called
scons-3.0.1
,
usually in your local directory.
Then change your working directory to that directory
and install SCons by executing the following commands:
#cd scons-3.0.1
#python setup.py install
This will build SCons,
install the scons
script
in the python which is used to run the setup.py's scripts directory
(/usr/local/bin
or
C:\Python25\Scripts
),
and will install the SCons build engine
in the corresponding library directory for the python used
(/usr/local/lib/scons
or
C:\Python25\scons
).
Because these are system directories,
you may need root (on Linux or UNIX) or Administrator (on Windows)
privileges to install SCons like this.
The SCons setup.py
script
has some extensions that support
easy installation of multiple versions of SCons
in side-by-side locations.
This makes it easier to download and
experiment with different versions of SCons
before moving your official build process to a new version,
for example.
To install SCons in a version-specific location,
add the --version-lib
option
when you call setup.py
:
# python setup.py install --version-lib
This will install the SCons build engine
in the
/usr/lib/scons-3.0.1
or
C:\Python25\scons-3.0.1
directory, for example.
If you use the --version-lib
option
the first time you install SCons,
you do not need to specify it each time you install
a new version.
The SCons setup.py
script
will detect the version-specific directory name(s)
and assume you want to install all versions
in version-specific directories.
You can override that assumption in the future
by explicitly specifying the --standalone-lib
option.
You can install SCons in locations other than
the default by specifying the --prefix=
option:
# python setup.py install --prefix=/opt/scons
This would
install the scons script in
/opt/scons/bin
and the build engine in
/opt/scons/lib/scons
,
Note that you can specify both the --prefix=
and the --version-lib
options
at the same type,
in which case setup.py
will install the build engine
in a version-specific directory
relative to the specified prefix.
Adding --version-lib
to the
above example would install the build engine in
/opt/scons/lib/scons-3.0.1
.
If you don't have the right privileges to install SCons
in a system location,
simply use the --prefix=
option
to install it in a location of your choosing.
For example,
to install SCons in appropriate locations
relative to the user's $HOME
directory,
the scons
script in
$HOME/bin
and the build engine in
$HOME/lib/scons
,
simply type:
$ python setup.py install --prefix=$HOME
You may, of course, specify any other location you prefer,
and may use the --version-lib
option
if you would like to install version-specific directories
relative to the specified prefix.
This can also be used to experiment with a newer
version of SCons than the one installed
in your system locations.
Of course, the location in which you install the
newer version of the scons
script
($HOME/bin
in the above example)
must be configured in your PATH
variable
before the directory containing
the system-installed version
of the scons
script.
In this chapter, you will see several examples of very simple build configurations using SCons, which will demonstrate how easy it is to use SCons to build programs from several different programming languages on different types of systems.
Here's the famous "Hello, World!" program in C:
int main() { printf("Hello, world!\n"); }
And here's how to build it using SCons.
Enter the following into a file named SConstruct
:
Program('hello.c')
This minimal configuration file gives
SCons two pieces of information:
what you want to build
(an executable program),
and the input file from
which you want it built
(the hello.c
file).
Program
is a builder_method,
a Python call that tells SCons that you want to build an
executable program.
That's it. Now run the scons
command to build the program.
On a POSIX-compliant system like Linux or UNIX,
you'll see something like:
% scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cc -o hello.o -c hello.c
cc -o hello hello.o
scons: done building targets.
On a Windows system with the Microsoft Visual C++ compiler, you'll see something like:
C:\>scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /Fohello.obj /c hello.c /nologo
link /nologo /OUT:hello.exe hello.obj
embedManifestExeCheck(target, source, env)
scons: done building targets.
First, notice that you only need to specify the name of the source file, and that SCons correctly deduces the names of the object and executable files to be built from the base of the source file name.
Second, notice that the same input SConstruct
file,
without any changes,
generates the correct output file names on both systems:
hello.o
and hello
on POSIX systems,
hello.obj
and hello.exe
on Windows systems.
This is a simple example of how SCons
makes it extremely easy to
write portable software builds.
(Note that we won't provide duplicate side-by-side POSIX and Windows output for all of the examples in this guide; just keep in mind that, unless otherwise specified, any of the examples should work equally well on both types of systems.)
The Program
builder method is only one of
many builder methods that SCons provides
to build different types of files.
Another is the Object
builder method,
which tells SCons to build an object file
from the specified source file:
Object('hello.c')
Now when you run the scons
command to build the program,
it will build just the hello.o
object file on a POSIX system:
% scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cc -o hello.o -c hello.c
scons: done building targets.
And just the hello.obj
object file
on a Windows system (with the Microsoft Visual C++ compiler):
C:\>scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /Fohello.obj /c hello.c /nologo
scons: done building targets.
SCons also makes building with Java extremely easy.
Unlike the Program
and Object
builder methods,
however, the Java
builder method
requires that you specify
the name of a destination directory in which
you want the class files placed,
followed by the source directory
in which the .java
files live:
Java('classes', 'src')
If the src
directory
contains a single hello.java
file,
then the output from running the scons
command
would look something like this
(on a POSIX system):
% scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
javac -d classes -sourcepath src src/hello.java
scons: done building targets.
We'll cover Java builds in more detail,
including building Java archive (.jar
)
and other types of file,
in Chapter 26, Java Builds.
When using SCons, it is unnecessary to add special
commands or target names to clean up after a build.
Instead, you simply use the
-c
or --clean
option when you invoke SCons,
and SCons removes the appropriate built files.
So if we build our example above
and then invoke scons -c
afterwards, the output on POSIX looks like:
%scons
scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... cc -o hello.o -c hello.c cc -o hello hello.o scons: done building targets. %scons -c
scons: Reading SConscript files ... scons: done reading SConscript files. scons: Cleaning targets ... Removed hello.o Removed hello scons: done cleaning targets.
And the output on Windows looks like:
C:\>scons
scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... cl /Fohello.obj /c hello.c /nologo link /nologo /OUT:hello.exe hello.obj embedManifestExeCheck(target, source, env) scons: done building targets. C:\>scons -c
scons: Reading SConscript files ... scons: done reading SConscript files. scons: Cleaning targets ... Removed hello.obj Removed hello.exe scons: done cleaning targets.
Notice that SCons changes its output to tell you that it
is Cleaning targets ...
and
done cleaning targets.
If you're used to build systems like Make
you've already figured out that the SConstruct
file
is the SCons equivalent of a Makefile
.
That is, the SConstruct
file is the input file
that SCons reads to control the build.
There is, however, an important difference between
an SConstruct
file and a Makefile
:
the SConstruct
file is actually a Python script.
If you're not already familiar with Python, don't worry.
This User's Guide will introduce you step-by-step
to the relatively small amount of Python you'll
need to know to be able to use SCons effectively.
And Python is very easy to learn.
One aspect of using Python as the
scripting language is that you can put comments
in your SConstruct
file using Python's commenting convention;
that is, everything between a '#' and the end of the line
will be ignored:
# Arrange to build the "hello" program. Program('hello.c') # "hello.c" is the source file.
You'll see throughout the remainder of this Guide that being able to use the power of a real scripting language can greatly simplify the solutions to complex requirements of real-world builds.
One important way in which the SConstruct
file is not exactly like a normal Python script,
and is more like a Makefile
,
is that the order in which
the SCons functions are called in
the SConstruct
file
does not
affect the order in which SCons
actually builds the programs and object files
you want it to build.[1]
In other words, when you call the Program
builder
(or any other builder method),
you're not telling SCons to build
the program at the instant the builder method is called.
Instead, you're telling SCons to build the program
that you want, for example,
a program built from a file named hello.c
,
and it's up to SCons to build that program
(and any other files) whenever it's necessary.
(We'll learn more about how
SCons decides when building or rebuilding a file
is necessary in Chapter 6, Dependencies, below.)
SCons reflects this distinction between
calling a builder method like Program
and actually building the program
by printing the status messages that indicate
when it's "just reading" the SConstruct
file,
and when it's actually building the target files.
This is to make it clear when SCons is
executing the Python statements that make up the SConstruct
file,
and when SCons is actually executing the
commands or other actions to
build the necessary files.
Let's clarify this with an example.
Python has a print
statement that
prints a string of characters to the screen.
If we put print
statements around
our calls to the Program
builder method:
print("Calling Program('hello.c')") Program('hello.c') print("Calling Program('goodbye.c')") Program('goodbye.c') print("Finished calling Program()")
Then when we execute SCons,
we see the output from the print
statements in between the messages about
reading the SConscript
files,
indicating that that is when the
Python statements are being executed:
% scons
scons: Reading SConscript files ...
Calling Program('hello.c')
Calling Program('goodbye.c')
Finished calling Program()
scons: done reading SConscript files.
scons: Building targets ...
cc -o goodbye.o -c goodbye.c
cc -o goodbye goodbye.o
cc -o hello.o -c hello.c
cc -o hello hello.o
scons: done building targets.
Notice also that SCons built the goodbye
program first,
even though the "reading SConscript
" output
shows that we called Program('hello.c')
first in the SConstruct
file.
You've already seen how SCons prints some messages about what it's doing, surrounding the actual commands used to build the software:
C:\>scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /Fohello.obj /c hello.c /nologo
link /nologo /OUT:hello.exe hello.obj
embedManifestExeCheck(target, source, env)
scons: done building targets.
These messages emphasize the
order in which SCons does its work:
all of the configuration files
(generically referred to as SConscript
files)
are read and executed first,
and only then are the target files built.
Among other benefits, these messages help to distinguish between
errors that occur while the configuration files are read,
and errors that occur while targets are being built.
One drawback, of course, is that these messages clutter the output.
Fortunately, they're easily disabled by using
the -Q
option when invoking SCons:
C:\>scons -Q
cl /Fohello.obj /c hello.c /nologo
link /nologo /OUT:hello.exe hello.obj
embedManifestExeCheck(target, source, env)
Because we want this User's Guide to focus
on what SCons is actually doing,
we're going to use the -Q
option
to remove these messages from the
output of all the remaining examples in this Guide.
[1] In programming parlance,
the SConstruct
file is
declarative,
meaning you tell SCons what you want done
and let it figure out the order in which to do it,
rather than strictly imperative,
where you specify explicitly the order in
which to do things.
In this chapter, you will see several examples of very simple build configurations using SCons, which will demonstrate how easy it is to use SCons to build programs from several different programming languages on different types of systems.
You've seen that when you call the Program
builder method,
it builds the resulting program with the same
base name as the source file.
That is, the following call to build an
executable program from the hello.c
source file
will build an executable program named hello
on POSIX systems,
and an executable program named hello.exe
on Windows systems:
Program('hello.c')
If you want to build a program with a different name than the base of the source file name, you simply put the target file name to the left of the source file name:
Program('new_hello', 'hello.c')
(SCons requires the target file name first,
followed by the source file name,
so that the order mimics that of an
assignment statement in most programming languages,
including Python:
"program = source files"
.)
Now SCons will build an executable program
named new_hello
when run on a POSIX system:
% scons -Q
cc -o hello.o -c hello.c
cc -o new_hello hello.o
And SCons will build an executable program
named new_hello.exe
when run on a Windows system:
C:\>scons -Q
cl /Fohello.obj /c hello.c /nologo
link /nologo /OUT:new_hello.exe hello.obj
embedManifestExeCheck(target, source, env)
You've just seen how to configure SCons to compile a program from a single source file. It's more common, of course, that you'll need to build a program from many input source files, not just one. To do this, you need to put the source files in a Python list (enclosed in square brackets), like so:
Program(['prog.c', 'file1.c', 'file2.c'])
A build of the above example would look like:
% scons -Q
cc -o file1.o -c file1.c
cc -o file2.o -c file2.c
cc -o prog.o -c prog.c
cc -o prog prog.o file1.o file2.o
Notice that SCons
deduces the output program name
from the first source file specified
in the list--that is,
because the first source file was prog.c
,
SCons will name the resulting program prog
(or prog.exe
on a Windows system).
If you want to specify a different program name,
then (as we've seen in the previous section)
you slide the list of source files
over to the right
to make room for the output program file name.
(SCons puts the output file name to the left
of the source file names
so that the order mimics that of an
assignment statement: "program = source files".)
This makes our example:
Program('program', ['prog.c', 'file1.c', 'file2.c'])
On Linux, a build of this example would look like:
% scons -Q
cc -o file1.o -c file1.c
cc -o file2.o -c file2.c
cc -o prog.o -c prog.c
cc -o program prog.o file1.o file2.o
Or on Windows:
C:\>scons -Q
cl /Fofile1.obj /c file1.c /nologo
cl /Fofile2.obj /c file2.c /nologo
cl /Foprog.obj /c prog.c /nologo
link /nologo /OUT:program.exe prog.obj file1.obj file2.obj
embedManifestExeCheck(target, source, env)
You can also use the Glob
function to find all files matching a
certain template, using the standard shell pattern matching
characters *
, ?
and [abc]
to match any of
a
, b
or c
.
[!abc]
is also supported,
to match any character except
a
, b
or c
.
This makes many multi-source-file builds quite easy:
Program('program', Glob('*.c'))
The SCons man page has more details on using Glob
with variant directories
(see Chapter 16, Variant Builds, below)
and repositories
(see Chapter 22, Building From Code Repositories, below),
excluding some files
and returning strings rather than Nodes.
We've now shown you two ways to specify the source for a program, one with a list of files:
Program('hello', ['file1.c', 'file2.c'])
And one with a single file:
Program('hello', 'hello.c')
You could actually put a single file name in a list, too, which you might prefer just for the sake of consistency:
Program('hello', ['hello.c'])
SCons functions will accept a single file name in either form. In fact, internally, SCons treats all input as lists of files, but allows you to omit the square brackets to cut down a little on the typing when there's only a single file name.
Although SCons functions are forgiving about whether or not you use a string vs. a list for a single file name, Python itself is more strict about treating lists and strings differently. So where SCons allows either a string or list:
# The following two calls both work correctly: Program('program1', 'program1.c') Program('program2', ['program2.c'])
Trying to do "Python things" that mix strings and lists will cause errors or lead to incorrect results:
common_sources = ['file1.c', 'file2.c'] # THE FOLLOWING IS INCORRECT AND GENERATES A PYTHON ERROR # BECAUSE IT TRIES TO ADD A STRING TO A LIST: Program('program1', common_sources + 'program1.c') # The following works correctly, because it's adding two # lists together to make another list. Program('program2', common_sources + ['program2.c'])
One drawback to the use of a Python list
for source files is that
each file name must be enclosed in quotes
(either single quotes or double quotes).
This can get cumbersome and difficult to read
when the list of file names is long.
Fortunately, SCons and Python provide a number of ways
to make sure that
the SConstruct
file stays easy to read.
To make long lists of file names
easier to deal with, SCons provides a
Split
function
that takes a quoted list of file names,
with the names separated by spaces or other white-space characters,
and turns it into a list of separate file names.
Using the Split
function turns the
previous example into:
Program('program', Split('main.c file1.c file2.c'))
(If you're already familiar with Python,
you'll have realized that this is similar to the
split()
method
in the Python standard string
module.
Unlike the split()
member function of strings,
however, the Split
function
does not require a string as input
and will wrap up a single non-string object in a list,
or return its argument untouched if it's already a list.
This comes in handy as a way to make sure
arbitrary values can be passed to SCons functions
without having to check the type of the variable by hand.)
Putting the call to the Split
function
inside the Program
call
can also be a little unwieldy.
A more readable alternative is to
assign the output from the Split
call
to a variable name,
and then use the variable when calling the
Program
function:
src_files = Split('main.c file1.c file2.c') Program('program', src_files)
Lastly, the Split
function
doesn't care how much white space separates
the file names in the quoted string.
This allows you to create lists of file
names that span multiple lines,
which often makes for easier editing:
src_files = Split("""main.c file1.c file2.c""") Program('program', src_files)
(Note in this example that we used the Python "triple-quote" syntax, which allows a string to contain multiple lines. The three quotes can be either single or double quotes.)
SCons also allows you to identify the output file and input source files using Python keyword arguments. The output file is known as the target, and the source file(s) are known (logically enough) as the source. The Python syntax for this is:
src_files = Split('main.c file1.c file2.c') Program(target = 'program', source = src_files)
Because the keywords explicitly identify what each argument is, you can actually reverse the order if you prefer:
src_files = Split('main.c file1.c file2.c') Program(source = src_files, target = 'program')
Whether or not you choose to use keyword arguments to identify the target and source files, and the order in which you specify them when using keywords, are purely personal choices; SCons functions the same regardless.
In order to compile multiple programs
within the same SConstruct
file,
simply call the Program
method
multiple times,
once for each program you need to build:
Program('foo.c') Program('bar', ['bar1.c', 'bar2.c'])
SCons would then build the programs as follows:
% scons -Q
cc -o bar1.o -c bar1.c
cc -o bar2.o -c bar2.c
cc -o bar bar1.o bar2.o
cc -o foo.o -c foo.c
cc -o foo foo.o
Notice that SCons does not necessarily build the
programs in the same order in which you specify
them in the SConstruct
file.
SCons does, however, recognize that
the individual object files must be built
before the resulting program can be built.
We'll discuss this in greater detail in
the "Dependencies" section, below.
It's common to re-use code by sharing source files between multiple programs. One way to do this is to create a library from the common source files, which can then be linked into resulting programs. (Creating libraries is discussed in Chapter 4, Building and Linking with Libraries, below.)
A more straightforward, but perhaps less convenient, way to share source files between multiple programs is simply to include the common files in the lists of source files for each program:
Program(Split('foo.c common1.c common2.c')) Program('bar', Split('bar1.c bar2.c common1.c common2.c'))
SCons recognizes that the object files for
the common1.c
and common2.c
source files
each need to be built only once,
even though the resulting object files are
each linked in to both of the resulting executable programs:
% scons -Q
cc -o bar1.o -c bar1.c
cc -o bar2.o -c bar2.c
cc -o common1.o -c common1.c
cc -o common2.o -c common2.c
cc -o bar bar1.o bar2.o common1.o common2.o
cc -o foo.o -c foo.c
cc -o foo foo.o common1.o common2.o
If two or more programs
share a lot of common source files,
repeating the common files in the list for each program
can be a maintenance problem when you need to change the
list of common files.
You can simplify this by creating a separate Python list
to hold the common file names,
and concatenating it with other lists
using the Python +
operator:
common = ['common1.c', 'common2.c'] foo_files = ['foo.c'] + common bar_files = ['bar1.c', 'bar2.c'] + common Program('foo', foo_files) Program('bar', bar_files)
This is functionally equivalent to the previous example.
It is possible to override or add construction variables when calling a builder method by passing additional keyword arguments. These overridden or added variables will only be in effect when building the target, so they will not affect other parts of the build. For example, if you want to add additional libraries for just one program:
env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])
or generate a shared library with a non-standard suffix:
env.SharedLibrary('word', 'word.cpp', SHLIBSUFFIX='.ocx', LIBSUFFIXES=['.ocx'])
It is also possible to use the parse_flags
keyword argument in an
override:
This example adds 'include' to $CPPPATH
,
'EBUG' to $CPPDEFINES
, and 'm' to $LIBS
.
env = Program('hello', 'hello.c', parse_flags = '-Iinclude -DEBUG -lm')
Within the call to the builder action the environment is not cloned, instead an OverrideEnvironment() is created which is more light weight than a whole Environment()
It's often useful to organize large software projects by collecting parts of the software into one or more libraries. SCons makes it easy to create libraries and to use them in the programs.
You build your own libraries by specifying Library
instead of Program
:
Library('foo', ['f1.c', 'f2.c', 'f3.c'])
SCons uses the appropriate library prefix and suffix for your system. So on POSIX or Linux systems, the above example would build as follows (although ranlib may not be called on all systems):
% scons -Q
cc -o f1.o -c f1.c
cc -o f2.o -c f2.c
cc -o f3.o -c f3.c
ar rc libfoo.a f1.o f2.o f3.o
ranlib libfoo.a
On a Windows system, a build of the above example would look like:
C:\>scons -Q
cl /Fof1.obj /c f1.c /nologo
cl /Fof2.obj /c f2.c /nologo
cl /Fof3.obj /c f3.c /nologo
lib /nologo /OUT:foo.lib f1.obj f2.obj f3.obj
The rules for the target name of the library are similar to those for programs: if you don't explicitly specify a target library name, SCons will deduce one from the name of the first source file specified, and SCons will add an appropriate file prefix and suffix if you leave them off.
The previous example shows building a library from a
list of source files.
You can, however, also give the Library
call
object files,
and it will correctly realize they are object files.
In fact, you can arbitrarily mix source code files
and object files in the source list:
Library('foo', ['f1.c', 'f2.o', 'f3.c', 'f4.o'])
And SCons realizes that only the source code files must be compiled into object files before creating the final library:
% scons -Q
cc -o f1.o -c f1.c
cc -o f3.o -c f3.c
ar rc libfoo.a f1.o f2.o f3.o f4.o
ranlib libfoo.a
Of course, in this example, the object files must already exist for the build to succeed. See Chapter 5, Node Objects, below, for information about how you can build object files explicitly and include the built files in a library.
The Library
function builds a traditional static library.
If you want to be explicit about the type of library being built,
you can use the synonym StaticLibrary
function
instead of Library
:
StaticLibrary('foo', ['f1.c', 'f2.c', 'f3.c'])
There is no functional difference between the
StaticLibrary
and Library
functions.
If you want to build a shared library (on POSIX systems)
or a DLL file (on Windows systems),
you use the SharedLibrary
function:
SharedLibrary('foo', ['f1.c', 'f2.c', 'f3.c'])
The output on POSIX:
% scons -Q
cc -o f1.os -c f1.c
cc -o f2.os -c f2.c
cc -o f3.os -c f3.c
cc -o libfoo.so -shared f1.os f2.os f3.os
And the output on Windows:
C:\>scons -Q
cl /Fof1.obj /c f1.c /nologo
cl /Fof2.obj /c f2.c /nologo
cl /Fof3.obj /c f3.c /nologo
link /nologo /dll /out:foo.dll /implib:foo.lib f1.obj f2.obj f3.obj
RegServerFunc(target, source, env)
embedManifestDllCheck(target, source, env)
Notice again that SCons takes care of
building the output file correctly,
adding the -shared
option
for a POSIX compilation,
and the /dll
option on Windows.
Usually, you build a library
because you want to link it with one or more programs.
You link libraries with a program by specifying
the libraries in the $LIBS
construction variable,
and by specifying the directory in which
the library will be found in the
$LIBPATH
construction variable:
Library('foo', ['f1.c', 'f2.c', 'f3.c']) Program('prog.c', LIBS=['foo', 'bar'], LIBPATH='.')
Notice, of course, that you don't need to specify a library
prefix (like lib
)
or suffix (like .a
or .lib
).
SCons uses the correct prefix or suffix for the current system.
On a POSIX or Linux system, a build of the above example would look like:
% scons -Q
cc -o f1.o -c f1.c
cc -o f2.o -c f2.c
cc -o f3.o -c f3.c
ar rc libfoo.a f1.o f2.o f3.o
ranlib libfoo.a
cc -o prog.o -c prog.c
cc -o prog prog.o -L. -lfoo -lbar
On a Windows system, a build of the above example would look like:
C:\>scons -Q
cl /Fof1.obj /c f1.c /nologo
cl /Fof2.obj /c f2.c /nologo
cl /Fof3.obj /c f3.c /nologo
lib /nologo /OUT:foo.lib f1.obj f2.obj f3.obj
cl /Foprog.obj /c prog.c /nologo
link /nologo /OUT:prog.exe /LIBPATH:. foo.lib bar.lib prog.obj
embedManifestExeCheck(target, source, env)
As usual, notice that SCons has taken care of constructing the correct command lines to link with the specified library on each system.
Note also that, if you only have a single library to link with, you can specify the library name in single string, instead of a Python list, so that:
Program('prog.c', LIBS='foo', LIBPATH='.')
is equivalent to:
Program('prog.c', LIBS=['foo'], LIBPATH='.')
This is similar to the way that SCons handles either a string or a list to specify a single source file.
By default, the linker will only look in
certain system-defined directories for libraries.
SCons knows how to look for libraries
in directories that you specify with the
$LIBPATH
construction variable.
$LIBPATH
consists of a list of
directory names, like so:
Program('prog.c', LIBS = 'm', LIBPATH = ['/usr/lib', '/usr/local/lib'])
Using a Python list is preferred because it's portable across systems. Alternatively, you could put all of the directory names in a single string, separated by the system-specific path separator character: a colon on POSIX systems:
LIBPATH = '/usr/lib:/usr/local/lib'
or a semi-colon on Windows systems:
LIBPATH = 'C:\\lib;D:\\lib'
(Note that Python requires that the backslash separators in a Windows path name be escaped within strings.)
When the linker is executed, SCons will create appropriate flags so that the linker will look for libraries in the same directories as SCons. So on a POSIX or Linux system, a build of the above example would look like:
% scons -Q
cc -o prog.o -c prog.c
cc -o prog prog.o -L/usr/lib -L/usr/local/lib -lm
On a Windows system, a build of the above example would look like:
C:\>scons -Q
cl /Foprog.obj /c prog.c /nologo
link /nologo /OUT:prog.exe /LIBPATH:\usr\lib /LIBPATH:\usr\local\lib m.lib prog.obj
embedManifestExeCheck(target, source, env)
Note again that SCons has taken care of the system-specific details of creating the right command-line options.
Internally, SCons represents all of the files
and directories it knows about as Nodes
.
These internal objects
(not object files)
can be used in a variety of ways
to make your SConscript
files portable and easy to read.
All builder methods return a list of
Node
objects that identify the
target file or files that will be built.
These returned Nodes
can be passed
as arguments to other builder methods.
For example, suppose that we want to build
the two object files that make up a program with different options.
This would mean calling the Object
builder once for each object file,
specifying the desired options:
Object('hello.c', CCFLAGS='-DHELLO') Object('goodbye.c', CCFLAGS='-DGOODBYE')
One way to combine these object files
into the resulting program
would be to call the Program
builder with the names of the object files
listed as sources:
Object('hello.c', CCFLAGS='-DHELLO') Object('goodbye.c', CCFLAGS='-DGOODBYE') Program(['hello.o', 'goodbye.o'])
The problem with specifying the names as strings
is that our SConstruct
file is no longer portable
across operating systems.
It won't, for example, work on Windows
because the object files there would be
named hello.obj
and goodbye.obj
,
not hello.o
and goodbye.o
.
A better solution is to assign the lists of targets
returned by the calls to the Object
builder to variables,
which we can then concatenate in our
call to the Program
builder:
hello_list = Object('hello.c', CCFLAGS='-DHELLO') goodbye_list = Object('goodbye.c', CCFLAGS='-DGOODBYE') Program(hello_list + goodbye_list)
This makes our SConstruct
file portable again,
the build output on Linux looking like:
% scons -Q
cc -o goodbye.o -c -DGOODBYE goodbye.c
cc -o hello.o -c -DHELLO hello.c
cc -o hello hello.o goodbye.o
And on Windows:
C:\>scons -Q
cl /Fogoodbye.obj /c goodbye.c -DGOODBYE
cl /Fohello.obj /c hello.c -DHELLO
link /nologo /OUT:hello.exe hello.obj goodbye.obj
embedManifestExeCheck(target, source, env)
We'll see examples of using the list of nodes returned by builder methods throughout the rest of this guide.
It's worth mentioning here that
SCons maintains a clear distinction
between Nodes that represent files
and Nodes that represent directories.
SCons supports File
and Dir
functions that, respectively,
return a file or directory Node:
hello_c = File('hello.c') Program(hello_c) classes = Dir('classes') Java(classes, 'src')
Normally, you don't need to call
File
or Dir
directly,
because calling a builder method automatically
treats strings as the names of files or directories,
and translates them into
the Node objects for you.
The File
and Dir
functions can come in handy
in situations where you need to explicitly
instruct SCons about the type of Node being
passed to a builder or other function,
or unambiguously refer to a specific
file in a directory tree.
There are also times when you may need to
refer to an entry in a file system
without knowing in advance
whether it's a file or a directory.
For those situations,
SCons also supports an Entry
function,
which returns a Node
that can represent either a file or a directory.
xyzzy = Entry('xyzzy')
The returned xyzzy
Node
will be turned into a file or directory Node
the first time it is used by a builder method
or other function that
requires one vs. the other.
One of the most common things you can do
with a Node is use it to print the
file name that the node represents.
Keep in mind, though, that because the object
returned by a builder call
is a list of Nodes,
you must use Python subscripts
to fetch individual Nodes from the list.
For example, the following SConstruct
file:
object_list = Object('hello.c') program_list = Program(object_list) print("The object file is: %s"%object_list[0]) print("The program file is: %s"%program_list[0])
Would print the following file names on a POSIX system:
% scons -Q
The object file is: hello.o
The program file is: hello
cc -o hello.o -c hello.c
cc -o hello hello.o
And the following file names on a Windows system:
C:\>scons -Q
The object file is: hello.obj
The program file is: hello.exe
cl /Fohello.obj /c hello.c /nologo
link /nologo /OUT:hello.exe hello.obj
embedManifestExeCheck(target, source, env)
Note that in the above example,
the object_list[0]
extracts an actual Node object
from the list,
and the Python print
statement
converts the object to a string for printing.
Printing a Node
's name
as described in the previous section
works because the string representation of a Node
object
is the name of the file.
If you want to do something other than
print the name of the file,
you can fetch it by using the builtin Python
str
function.
For example, if you want to use the Python
os.path.exists
to figure out whether a file
exists while the SConstruct
file
is being read and executed,
you can fetch the string as follows:
import os.path program_list = Program('hello.c') program_name = str(program_list[0]) if not os.path.exists(program_name): print("%s does not exist!"%program_name)
Which executes as follows on a POSIX system:
% scons -Q
hello does not exist!
cc -o hello.o -c hello.c
cc -o hello hello.o
env.GetBuildPath(file_or_list)
returns the path of a Node
or a string representing a
path. It can also take a list of Node
s and/or strings, and
returns the list of paths. If passed a single Node
, the result
is the same as calling str(node)
(see above).
The string(s) can have embedded construction variables, which are
expanded as usual, using the calling environment's set of
variables. The paths can be files or directories, and do not have
to exist.
env=Environment(VAR="value") n=File("foo.c") print(env.GetBuildPath([n, "sub/dir/$VAR"]))
Would print the following file names:
% scons -Q
['foo.c', 'sub/dir/value']
scons: `.' is up to date.
There is also a function version of GetBuildPath
which can
be called without an Environment
; that uses the default SCons
Environment
to do substitution on any string arguments.
So far we've seen how SCons handles one-time builds.
But one of the main functions of a build tool like SCons
is to rebuild only what is necessary
when source files change--or, put another way,
SCons should not
waste time rebuilding things that don't need to be rebuilt.
You can see this at work simply by re-invoking SCons
after building our simple hello
example:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q
scons: `.' is up to date.
The second time it is executed,
SCons realizes that the hello
program
is up-to-date with respect to the current hello.c
source file,
and avoids rebuilding it.
You can see this more clearly by naming
the hello
program explicitly on the command line:
%scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date.
Note that SCons reports "...is up to date"
only for target files named explicitly on the command line,
to avoid cluttering the output.
Another aspect of avoiding unnecessary rebuilds
is the fundamental build tool behavior
of rebuilding
things when an input file changes,
so that the built software is up to date.
By default,
SCons keeps track of this through an
MD5 signature
, or checksum, of the contents of each file,
although you can easily configure
SCons to use the
modification times (or time stamps)
instead.
You can even specify your own Python function
for deciding if an input file has changed.
By default, SCons keeps track of whether a file has changed based on an MD5 checksum of the file's contents, not the file's modification time. This means that you may be surprised by the default SCons behavior if you are used to the Make convention of forcing a rebuild by updating the file's modification time (using the touch command, for example):
%scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o %touch hello.c
%scons -Q hello
scons: `hello' is up to date.
Even though the file's modification time has changed,
SCons realizes that the contents of the
hello.c
file have not changed,
and therefore that the hello
program
need not be rebuilt.
This avoids unnecessary rebuilds when,
for example, someone rewrites the
contents of a file without making a change.
But if the contents of the file really do change,
then SCons detects the change
and rebuilds the program as required:
%scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o % [CHANGE THE CONTENTS OF hello.c] %scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o
Note that you can, if you wish,
specify this default behavior
(MD5 signatures) explicitly
using the Decider
function as follows:
Program('hello.c') Decider('MD5')
You can also use the string 'content'
as a synonym for 'MD5'
when calling the Decider
function.
Using MD5 signatures to decide if an input file has changed has one surprising benefit: if a source file has been changed in such a way that the contents of the rebuilt target file(s) will be exactly the same as the last time the file was built, then any "downstream" target files that depend on the rebuilt-but-not-changed target file actually need not be rebuilt.
So if, for example,
a user were to only change a comment in a hello.c
file,
then the rebuilt hello.o
file
would be exactly the same as the one previously built
(assuming the compiler doesn't put any build-specific
information in the object file).
SCons would then realize that it would not
need to rebuild the hello
program as follows:
%scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o % [CHANGE A COMMENT IN hello.c] %scons -Q hello
cc -o hello.o -c hello.c scons: `hello' is up to date.
In essence, SCons
"short-circuits" any dependent builds
when it realizes that a target file
has been rebuilt to exactly the same file as the last build.
This does take some extra processing time
to read the contents of the target (hello.o
) file,
but often saves time when the rebuild that was avoided
would have been time-consuming and expensive.
If you prefer, you can configure SCons to use the modification time of a file, not the file contents, when deciding if a target needs to be rebuilt. SCons gives you two ways to use time stamps to decide if an input file has changed since the last time a target has been built.
The most familiar way to use time stamps
is the way Make does:
that is, have SCons decide
that a target must be rebuilt
if a source file's modification time is
newer
than the target file.
To do this, call the Decider
function as follows:
Object('hello.c') Decider('timestamp-newer')
This makes SCons act like Make when a file's modification time is updated (using the touch command, for example):
%scons -Q hello.o
cc -o hello.o -c hello.c %touch hello.c
%scons -Q hello.o
cc -o hello.o -c hello.c
And, in fact, because this behavior is the same
as the behavior of Make,
you can also use the string 'make'
as a synonym for 'timestamp-newer'
when calling the Decider
function:
Object('hello.c') Decider('make')
One drawback to using times stamps exactly like Make is that if an input file's modification time suddenly becomes older than a target file, the target file will not be rebuilt. This can happen if an old copy of a source file is restored from a backup archive, for example. The contents of the restored file will likely be different than they were the last time a dependent target was built, but the target won't be rebuilt because the modification time of the source file is not newer than the target.
Because SCons actually stores information
about the source files' time stamps whenever a target is built,
it can handle this situation by checking for
an exact match of the source file time stamp,
instead of just whether or not the source file
is newer than the target file.
To do this, specify the argument
'timestamp-match'
when calling the Decider
function:
Object('hello.c') Decider('timestamp-match')
When configured this way,
SCons will rebuild a target whenever
a source file's modification time has changed.
So if we use the touch -t
option to change the modification time of
hello.c
to an old date (January 1, 1989),
SCons will still rebuild the target file:
%scons -Q hello.o
cc -o hello.o -c hello.c %touch -t 198901010000 hello.c
%scons -Q hello.o
cc -o hello.o -c hello.c
In general, the only reason to prefer
timestamp-newer
instead of
timestamp-match
,
would be if you have some specific reason
to require this Make-like behavior of
not rebuilding a target when an otherwise-modified
source file is older.
As a performance enhancement,
SCons provides a way to use
MD5 checksums of file contents
but to read those contents
only when the file's timestamp has changed.
To do this, call the Decider
function with 'MD5-timestamp'
argument as follows:
Program('hello.c') Decider('MD5-timestamp')
So configured, SCons will still behave like
it does when using Decider('MD5')
:
%scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o %touch hello.c
%scons -Q hello
scons: `hello' is up to date. %edit hello.c
[CHANGE THE CONTENTS OF hello.c] %scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o
However, the second call to SCons in the above output,
when the build is up-to-date,
will have been performed by simply looking at the
modification time of the hello.c
file,
not by opening it and performing
an MD5 checksum calcuation on its contents.
This can significantly speed up many up-to-date builds.
The only drawback to using
Decider('MD5-timestamp')
is that SCons will not
rebuild a target file if a source file was modified
within one second of the last time SCons built the file.
While most developers are programming,
this isn't a problem in practice,
since it's unlikely that someone will have built
and then thought quickly enough to make a substantive
change to a source file within one second.
Certain build scripts or
continuous integration tools may, however,
rely on the ability to apply changes to files
automatically and then rebuild as quickly as possible,
in which case use of
Decider('MD5-timestamp')
may not be appropriate.
The different string values that we've passed to
the Decider
function are essentially used by SCons
to pick one of several specific internal functions
that implement various ways of deciding if a dependency
(usually a source file)
has changed since a target file has been built.
As it turns out,
you can also supply your own function
to decide if a dependency has changed.
For example, suppose we have an input file
that contains a lot of data,
in some specific regular format,
that is used to rebuild a lot of different target files,
but each target file really only depends on
one particular section of the input file.
We'd like to have each target file depend on
only its section of the input file.
However, since the input file may contain a lot of data,
we want to open the input file only if its timestamp has changed.
This could be done with a custom
Decider
function that might look something like this:
Program('hello.c') def decide_if_changed(dependency, target, prev_ni): if self.get_timestamp() != prev_ni.timestamp: dep = str(dependency) tgt = str(target) if specific_part_of_file_has_changed(dep, tgt): return True return False Decider(decide_if_changed)
Note that in the function definition,
the dependency
(input file) is the first argument,
and then the target
.
Both of these are passed to the functions as
SCons Node
objects,
which we convert to strings using the Python
str()
.
The third argument, prev_ni
,
is an object that holds the
signature or timestamp information
that was recorded about the dependency
the last time the target was built.
A prev_ni
object can hold
different information,
depending on the type of thing that the
dependency
argument represents.
For normal files,
the prev_ni
object
has the following attributes:
The content signature,
or MD5 checksum, of the contents of the
dependency
file the list time the target
was built.
The size in bytes of the dependency
file the list time the target was built.
The modification time of the dependency
file the list time the target
was built.
Note that ignoring some of the arguments
in your custom Decider
function
is a perfectly normal thing to do,
if they don't impact the way you want to
decide if the dependency file has changed.
Another thing to look out for is the fact that the three
attributes above may not be present at the time of the first run.
Without any prior build, no targets have been created and no
.sconsign
DB file exists yet.
So, you should always check whether the
prev_ni
attribute in question is available.
We finally present a small example for a
csig
-based decider function. Note how the
signature information for the dependency
file
has to get initialized via get_csig
during each function call (this is mandatory!).
env = Environment() def config_file_decider(dependency, target, prev_ni): import os.path # We always have to init the .csig value... dep_csig = dependency.get_csig() # .csig may not exist, because no target was built yet... if 'csig' not in dir(prev_ni): return True # Target file may not exist yet if not os.path.exists(str(target.abspath)): return True if dep_csig != prev_ni.csig: # Some change on source file => update installed one return True return False def update_file(): f = open("test.txt","a") f.write("some line\n") f.close() update_file() # Activate our own decider function env.Decider(config_file_decider) env.Install("install","test.txt")
The previous examples have all demonstrated calling
the global Decider
function
to configure all dependency decisions that SCons makes.
Sometimes, however, you want to be able to configure
different decision-making for different targets.
When that's necessary, you can use the
env.Decider
method to affect only the configuration
decisions for targets built with a
specific construction environment.
For example, if we arbitrarily want to build one program using MD5 checkums and another using file modification times from the same source we might configure it this way:
env1 = Environment(CPPPATH = ['.']) env2 = env1.Clone() env2.Decider('timestamp-match') env1.Program('prog-MD5', 'program1.c') env2.Program('prog-timestamp', 'program2.c')
If both of the programs include the same
inc.h
file,
then updating the modification time of
inc.h
(using the touch command)
will cause only prog-timestamp
to be rebuilt:
%scons -Q
cc -o program1.o -c -I. program1.c cc -o prog-MD5 program1.o cc -o program2.o -c -I. program2.c cc -o prog-timestamp program2.o %touch inc.h
%scons -Q
cc -o program2.o -c -I. program2.c cc -o prog-timestamp program2.o
SCons still supports two functions that used to be the
primary methods for configuring the
decision about whether or not an input file has changed.
These functions have been officially deprecated
as SCons version 2.0,
and their use is discouraged,
mainly because they rely on a somewhat
confusing distinction between how
source files and target files are handled.
These functions are documented here mainly in case you
encounter them in older SConscript
files.
The SourceSignatures
function is fairly straightforward,
and supports two different argument values
to configure whether source file changes should be decided
using MD5 signatures:
Program('hello.c') SourceSignatures('MD5')
Or using time stamps:
Program('hello.c') SourceSignatures('timestamp')
These are roughly equivalent to specifying
Decider('MD5')
or
Decider('timestamp-match')
,
respectively,
although it only affects how SCons makes
decisions about dependencies on
source files--that is,
files that are not built from any other files.
The TargetSignatures
function
specifies how SCons decides
when a target file has changed
when it is used as a
dependency of (input to) another target--that is,
the TargetSignatures
function configures
how the signatures of "intermediate" target files
are used when deciding if a "downstream" target file
must be rebuilt.
[2]
The TargetSignatures
function supports the same
'MD5'
and 'timestamp'
argument values that are supported by the SourceSignatures
,
with the same meanings, but applied to target files.
That is, in the example:
Program('hello.c') TargetSignatures('MD5')
The MD5 checksum of the hello.o
target file
will be used to decide if it has changed since the last
time the "downstream" hello
target file was built.
And in the example:
Program('hello.c') TargetSignatures('timestamp')
The modification time of the hello.o
target file
will be used to decide if it has changed since the last
time the "downstream" hello
target file was built.
The TargetSignatures
function supports
two additional argument values:
'source'
and 'build'
.
The 'source'
argument
specifies that decisions involving
whether target files have changed
since a previous build
should use the same behavior
for the decisions configured for source files
(using the SourceSignatures
function).
So in the example:
Program('hello.c') TargetSignatures('source') SourceSignatures('timestamp')
All files, both targets and sources, will use modification times when deciding if an input file has changed since the last time a target was built.
Lastly, the 'build'
argument
specifies that SCons should examine
the build status of a target file
and always rebuild a "downstream" target
if the target file was itself rebuilt,
without re-examining the contents or timestamp
of the newly-built target file.
If the target file was not rebuilt during
this scons
invocation,
then the target file will be examined
the same way as configured by
the SourceSignature
call
to decide if it has changed.
This mimics the behavior of
build signatures
in earlier versions of SCons.
A build signature
re-combined
signatures of all the input files
that went into making the target file,
so that the target file itself
did not need to have its contents read
to compute an MD5 signature.
This can improve performance for some configurations,
but is generally not as effective as using
Decider('MD5-timestamp')
.
Now suppose that our "Hello, World!" program
actually has an #include
line
to include the hello.h
file in the compilation:
#include <hello.h> int main() { printf("Hello, %s!\n", string); }
And, for completeness, the hello.h
file looks like this:
#define string "world"
In this case, we want SCons to recognize that,
if the contents of the hello.h
file change,
the hello
program must be recompiled.
To do this, we need to modify the
SConstruct
file like so:
Program('hello.c', CPPPATH = '.')
The $CPPPATH
value
tells SCons to look in the current directory
('.'
)
for any files included by C source files
(.c
or .h
files).
With this assignment in the SConstruct
file:
%scons -Q hello
cc -o hello.o -c -I. hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date. % [CHANGE THE CONTENTS OF hello.h] %scons -Q hello
cc -o hello.o -c -I. hello.c cc -o hello hello.o
First, notice that SCons
added the -I.
argument
from the $CPPPATH
variable
so that the compilation would find the
hello.h
file in the local directory.
Second, realize that SCons knows that the hello
program must be rebuilt
because it scans the contents of
the hello.c
file
for the #include
lines that indicate
another file is being included in the compilation.
SCons records these as
implicit dependencies
of the target file,
Consequently,
when the hello.h
file changes,
SCons realizes that the hello.c
file includes it,
and rebuilds the resulting hello
program
that depends on both the hello.c
and hello.h
files.
Like the $LIBPATH
variable,
the $CPPPATH
variable
may be a list of directories,
or a string separated by
the system-specific path separation character
(':' on POSIX/Linux, ';' on Windows).
Either way, SCons creates the
right command-line options
so that the following example:
Program('hello.c', CPPPATH = ['include', '/home/project/inc'])
Will look like this on POSIX or Linux:
% scons -Q hello
cc -o hello.o -c -Iinclude -I/home/project/inc hello.c
cc -o hello hello.o
And like this on Windows:
C:\>scons -Q hello.exe
cl /Fohello.obj /c hello.c /nologo /Iinclude /I\home\project\inc
link /nologo /OUT:hello.exe hello.obj
embedManifestExeCheck(target, source, env)
Scanning each file for #include
lines
does take some extra processing time.
When you're doing a full build of a large system,
the scanning time is usually a very small percentage
of the overall time spent on the build.
You're most likely to notice the scanning time,
however, when you rebuild
all or part of a large system:
SCons will likely take some extra time to "think about"
what must be built before it issues the
first build command
(or decides that everything is up to date
and nothing must be rebuilt).
In practice, having SCons scan files saves time
relative to the amount of potential time
lost to tracking down subtle problems
introduced by incorrect dependencies.
Nevertheless, the "waiting time"
while SCons scans files can annoy
individual developers waiting for their builds to finish.
Consequently, SCons lets you cache
the implicit dependencies
that its scanners find,
for use by later builds.
You can do this by specifying the
--implicit-cache
option on the command line:
%scons -Q --implicit-cache hello
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date.
If you don't want to specify --implicit-cache
on the command line each time,
you can make it the default behavior for your build
by setting the implicit_cache
option
in an SConscript
file:
SetOption('implicit_cache', 1)
SCons does not cache implicit dependencies like this by default
because the --implicit-cache
causes SCons to simply use the implicit
dependencies stored during the last run, without any checking
for whether or not those dependencies are still correct.
Specifically, this means --implicit-cache
instructs SCons
to not rebuild "correctly" in the
following cases:
When --implicit-cache
is used, SCons will ignore any changes that
may have been made to search paths
(like $CPPPATH
or $LIBPATH
,).
This can lead to SCons not rebuilding a file if a change to
$CPPPATH
would normally cause a different, same-named file from
a different directory to be used.
When --implicit-cache
is used, SCons will not detect if a
same-named file has been added to a directory that is earlier in
the search path than the directory in which the file was found
last time.
When using cached implicit dependencies,
sometimes you want to "start fresh"
and have SCons re-scan the files
for which it previously cached the dependencies.
For example,
if you have recently installed a new version of
external code that you use for compilation,
the external header files will have changed
and the previously-cached implicit dependencies
will be out of date.
You can update them by
running SCons with the --implicit-deps-changed
option:
%scons -Q --implicit-deps-changed hello
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date.
In this case, SCons will re-scan all of the implicit dependencies and cache updated copies of the information.
By default when caching dependencies,
SCons notices when a file has been modified
and re-scans the file for any updated
implicit dependency information.
Sometimes, however, you may want
to force SCons to use the cached implicit dependencies,
even if the source files changed.
This can speed up a build for example,
when you have changed your source files
but know that you haven't changed
any #include
lines.
In this case,
you can use the --implicit-deps-unchanged
option:
%scons -Q --implicit-deps-unchanged hello
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date.
In this case, SCons will assume that the cached implicit dependencies are correct and will not bother to re-scan changed files. For typical builds after small, incremental changes to source files, the savings may not be very big, but sometimes every bit of improved performance counts.
Sometimes a file depends on another file
that is not detected by an SCons scanner.
For this situation,
SCons allows you to specific explicitly that one file
depends on another file,
and must be rebuilt whenever that file changes.
This is specified using the Depends
method:
hello = Program('hello.c') Depends(hello, 'other_file')
%scons -Q hello
cc -c hello.c -o hello.o cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date. %edit other_file
[CHANGE THE CONTENTS OF other_file] %scons -Q hello
cc -c hello.c -o hello.o cc -o hello hello.o
Note that the dependency
(the second argument to Depends
)
may also be a list of Node objects
(for example, as returned by a call to a Builder):
hello = Program('hello.c') goodbye = Program('goodbye.c') Depends(hello, goodbye)
in which case the dependency or dependencies will be built before the target(s):
% scons -Q hello
cc -c goodbye.c -o goodbye.o
cc -o goodbye goodbye.o
cc -c hello.c -o hello.o
cc -o hello hello.o
SCons has built-in scanners for a number of languages. Sometimes these scanners fail to extract certain implicit dependencies due to limitations of the scanner implementation.
The following example illustrates a case where the built-in C scanner is unable to extract the implicit dependency on a header file.
#define FOO_HEADER <foo.h> #include FOO_HEADER int main() { return FOO; }
%scons -Q
cc -o hello.o -c -I. hello.c cc -o hello hello.o % [CHANGE CONTENTS OF foo.h] %scons -Q
scons: `.' is up to date.
Apparently, the scanner does not know about the header dependency. Being not a full-fledged C preprocessor, the scanner does not expand the macro.
In these cases, you may also use the compiler to extract the
implicit dependencies. ParseDepends
can parse the contents of
the compiler output in the style of Make, and explicitly
establish all of the listed dependencies.
The following example uses ParseDepends
to process a compiler
generated dependency file which is generated as a side effect
during compilation of the object file:
obj = Object('hello.c', CCFLAGS='-MD -MF hello.d', CPPPATH='.') SideEffect('hello.d', obj) ParseDepends('hello.d') Program('hello', obj)
%scons -Q
cc -o hello.o -c -MD -MF hello.d -I. hello.c cc -o hello hello.o % [CHANGE CONTENTS OF foo.h] %scons -Q
cc -o hello.o -c -MD -MF hello.d -I. hello.c
Parsing dependencies from a compiler-generated
.d
file has a chicken-and-egg problem, that
causes unnecessary rebuilds:
%scons -Q
cc -o hello.o -c -MD -MF hello.d -I. hello.c cc -o hello hello.o %scons -Q --debug=explain
scons: rebuilding `hello.o' because `foo.h' is a new dependency cc -o hello.o -c -MD -MF hello.d -I. hello.c %scons -Q
scons: `.' is up to date.
In the first pass, the dependency file is generated while the
object file is compiled. At that time, SCons does not know about
the dependency on foo.h
. In the second pass,
the object file is regenerated because foo.h
is detected as a new dependency.
ParseDepends
immediately reads the specified file at invocation
time and just returns if the file does not exist. A dependency
file generated during the build process is not automatically
parsed again. Hence, the compiler-extracted dependencies are not
stored in the signature database during the same build pass. This
limitation of ParseDepends
leads to unnecessary recompilations.
Therefore, ParseDepends
should only be used if scanners are not
available for the employed language or not powerful enough for the
specific task.
Sometimes it makes sense to not rebuild a program, even if a dependency file changes. In this case, you would tell SCons specifically to ignore a dependency as follows:
hello_obj=Object('hello.c') hello = Program(hello_obj) Ignore(hello_obj, 'hello.h')
%scons -Q hello
cc -c -o hello.o hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date. %edit hello.h
[CHANGE THE CONTENTS OF hello.h] %scons -Q hello
scons: `hello' is up to date.
Now, the above example is a little contrived,
because it's hard to imagine a real-world situation
where you wouldn't want to rebuild hello
if the hello.h
file changed.
A more realistic example
might be if the hello
program is being built in a
directory that is shared between multiple systems
that have different copies of the
stdio.h
include file.
In that case,
SCons would notice the differences between
the different systems' copies of stdio.h
and would rebuild hello
each time you change systems.
You could avoid these rebuilds as follows:
hello = Program('hello.c', CPPPATH=['/usr/include']) Ignore(hello, '/usr/include/stdio.h')
Ignore
can also be used to prevent a generated file from being built
by default. This is due to the fact that directories depend on
their contents. So to ignore a generated file from the default build,
you specify that the directory should ignore the generated file.
Note that the file will still be built if the user specifically
requests the target on scons command line, or if the file is
a dependency of another file which is requested and/or is built
by default.
hello_obj=Object('hello.c') hello = Program(hello_obj) Ignore('.',[hello,hello_obj])
%scons -Q
scons: `.' is up to date. %scons -Q hello
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q hello
scons: `hello' is up to date.
Occasionally, it may be useful to specify that a certain file or directory must, if necessary, be built or created before some other target is built, but that changes to that file or directory do not require that the target itself be rebuilt. Such a relationship is called an order-only dependency because it only affects the order in which things must be built--the dependency before the target--but it is not a strict dependency relationship because the target should not change in response to changes in the dependent file.
For example, suppose that you want to create a file
every time you run a build
that identifies the time the build was performed,
the version number, etc.,
and which is included in every program that you build.
The version file's contents will change every build.
If you specify a normal dependency relationship,
then every program that depends on
that file would be rebuilt every time you ran SCons.
For example, we could use some Python code in
a SConstruct
file to create a new version.c
file
with a string containing the current date every time
we run SCons,
and then link a program with the resulting object file
by listing version.c
in the sources:
import time version_c_text = """ char *date = "%s"; """ % time.ctime(time.time()) open('version.c', 'w').write(version_c_text) hello = Program(['hello.c', 'version.c'])
If we list version.c
as an actual source file,
though, then the version.o
file
will get rebuilt every time we run SCons
(because the SConstruct
file itself changes
the contents of version.c
)
and the hello
executable
will get re-linked every time
(because the version.o
file changes):
%scons -Q hello
cc -o hello.o -c hello.c cc -o version.o -c version.c cc -o hello hello.o version.o %sleep 1
%scons -Q hello
cc -o version.o -c version.c cc -o hello hello.o version.o %sleep 1
%scons -Q hello
cc -o version.o -c version.c cc -o hello hello.o version.o
(Note that for the above example to work,
we sleep for one second in between each run,
so that the SConstruct
file will create a
version.c
file with a time string
that's one second later than the previous run.)
One solution is to use the Requires
function
to specify that the version.o
must be rebuilt before it is used by the link step,
but that changes to version.o
should not actually cause the hello
executable to be re-linked:
import time version_c_text = """ char *date = "%s"; """ % time.ctime(time.time()) open('version.c', 'w').write(version_c_text) version_obj = Object('version.c') hello = Program('hello.c', LINKFLAGS = str(version_obj[0])) Requires(hello, version_obj)
Notice that because we can no longer list version.c
as one of the sources for the hello
program,
we have to find some other way to get it into the link command line.
For this example, we're cheating a bit and stuffing the
object file name (extracted from version_obj
list returned by the Object
call)
into the $LINKFLAGS
variable,
because $LINKFLAGS
is already included
in the $LINKCOM
command line.
With these changes,
we get the desired behavior of only
re-linking the hello
executable
when the hello.c
has changed,
even though the version.o
is rebuilt
(because the SConstruct
file still changes the
version.c
contents directly each run):
%scons -Q hello
cc -o version.o -c version.c cc -o hello.o -c hello.c cc -o hello version.o hello.o %sleep 1
%scons -Q hello
cc -o version.o -c version.c scons: `hello' is up to date. %sleep 1
% [CHANGE THE CONTENTS OF hello.c] %scons -Q hello
cc -o version.o -c version.c cc -o hello.o -c hello.c cc -o hello version.o hello.o %sleep 1
%scons -Q hello
cc -o version.o -c version.c scons: `hello' is up to date.
How SCons handles dependencies can also be affected
by the AlwaysBuild
method.
When a file is passed to the AlwaysBuild
method,
like so:
hello = Program('hello.c') AlwaysBuild(hello)
Then the specified target file (hello
in our example)
will always be considered out-of-date and
rebuilt whenever that target file is evaluated
while walking the dependency graph:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q
cc -o hello hello.o
The AlwaysBuild
function has a somewhat misleading name,
because it does not actually mean the target file will
be rebuilt every single time SCons is invoked.
Instead, it means that the target will, in fact,
be rebuilt whenever the target file is encountered
while evaluating the targets specified on
the command line (and their dependencies).
So specifying some other target on the command line,
a target that does not
itself depend on the AlwaysBuild
target,
will still be rebuilt only if it's out-of-date
with respect to its dependencies:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q hello.o
scons: `hello.o' is up to date.
[2]
This easily-overlooked distinction between
how SCons decides if the target itself must be rebuilt
and how the target is then used to decide if a different
target must be rebuilt is one of the confusing
things that has led to the TargetSignatures
and SourceSignatures
functions being
replaced by the simpler Decider
function.
An environment
is a collection of values that
can affect how a program executes.
SCons distinguishes between three
different types of environments
that can affect the behavior of SCons itself
(subject to the configuration in the SConscript
files),
as well as the compilers and other tools it executes:
The external environment
is the set of variables in the user's environment
at the time the user runs SCons.
These variables are available within the SConscript
files
through the Python os.environ
dictionary.
See Section 7.1, “Using Values From the External Environment”, below.
Construction Environment
A construction environment
is a distinct object creating within
a SConscript
file and
and which contains values that
affect how SCons decides
what action to use to build a target,
and even to define which targets
should be built from which sources.
One of the most powerful features of SCons
is the ability to create multiple construction environments
,
including the ability to clone a new, customized
construction environment
from an existing construction environment
.
See Section 7.2, “Construction Environments”, below.
An execution environment
is the values that SCons sets
when executing an external
command (such as a compiler or linker)
to build one or more targets.
Note that this is not the same as
the external environment
(see above).
See Section 7.3, “Controlling the Execution Environment for Issued Commands”, below.
Unlike Make, SCons does not automatically
copy or import values between different environments
(with the exception of explicit clones of construction environments
,
which inherit values from their parent).
This is a deliberate design choice
to make sure that builds are,
by default, repeatable regardless of
the values in the user's external environment.
This avoids a whole class of problems with builds
where a developer's local build works
because a custom variable setting
causes a different compiler or build option to be used,
but the checked-in change breaks the official build
because it uses different environment variable settings.
Note that the SConscript
writer can
easily arrange for variables to be
copied or imported between environments,
and this is often very useful
(or even downright necessary)
to make it easy for developers
to customize the build in appropriate ways.
The point is not
that copying variables between different environments
is evil and must always be avoided.
Instead, it should be up to the
implementer of the build system
to make conscious choices
about how and when to import
a variable from one environment to another,
making informed decisions about
striking the right balance
between making the build
repeatable on the one hand
and convenient to use on the other.
The external environment
variable settings that
the user has in force
when executing SCons
are available through the normal Python
os.environ
dictionary.
This means that you must add an
import os
statement
to any SConscript
file
in which you want to use
values from the user's external environment.
import os
More usefully, you can use the
os.environ
dictionary in your SConscript
files to initialize construction environments
with values from the user's external environment.
See the next section,
Section 7.2, “Construction Environments”,
for information on how to do this.
It is rare that all of the software in a large,
complicated system needs to be built the same way.
For example, different source files may need different options
enabled on the command line,
or different executable programs need to be linked
with different libraries.
SCons accommodates these different build
requirements by allowing you to create and
configure multiple construction environments
that control how the software is built.
A construction environment
is an object
that has a number of associated
construction variables
, each with a name and a value.
(A construction environment also has an attached
set of Builder
methods,
about which we'll learn more later.)
A construction environment
is created by the Environment
method:
env = Environment()
By default, SCons initializes every
new construction environment
with a set of construction variables
based on the tools that it finds on your system,
plus the default set of builder methods
necessary for using those tools.
The construction variables
are initialized with values describing
the C compiler,
the Fortran compiler,
the linker,
etc.,
as well as the command lines to invoke them.
When you initialize a construction environment
you can set the values of the
environment's construction variables
to control how a program is built.
For example:
env = Environment(CC = 'gcc', CCFLAGS = '-O2') env.Program('foo.c')
The construction environment in this example
is still initialized with the same default
construction variable values,
except that the user has explicitly specified use of the
GNU C compiler gcc,
and further specifies that the -O2
(optimization level two)
flag should be used when compiling the object file.
In other words, the explicit initializations of
$CC
and $CCFLAGS
override the default values in the newly-created
construction environment.
So a run from this example would look like:
% scons -Q
gcc -o foo.o -c -O2 foo.c
gcc -o foo foo.o
You can fetch individual construction variables using the normal syntax for accessing individual named items in a Python dictionary:
env = Environment() print("CC is: %s"%env['CC'])
This example SConstruct
file doesn't build anything,
but because it's actually a Python script,
it will print the value of $CC
for us:
% scons -Q
CC is: cc
scons: `.' is up to date.
A construction environment, however,
is actually an object with associated methods, etc.
If you want to have direct access to only the
dictionary of construction variables,
you can fetch this using the Dictionary
method:
env = Environment(FOO = 'foo', BAR = 'bar') dict = env.Dictionary() for key in ['OBJSUFFIX', 'LIBSUFFIX', 'PROGSUFFIX']: print("key = %s, value = %s" % (key, dict[key]))
This SConstruct
file
will print the specified dictionary items for us on POSIX
systems as follows:
% scons -Q
key = OBJSUFFIX, value = .o
key = LIBSUFFIX, value = .a
key = PROGSUFFIX, value =
scons: `.' is up to date.
And on Windows:
C:\>scons -Q
key = OBJSUFFIX, value = .obj
key = LIBSUFFIX, value = .lib
key = PROGSUFFIX, value = .exe
scons: `.' is up to date.
If you want to loop and print the values of all of the construction variables in a construction environment, the Python code to do that in sorted order might look something like:
env = Environment() for item in sorted(env.Dictionary().items()): print("construction variable = '%s', value = '%s'" % item)
Another way to get information from
a construction environment
is to use the subst
method
on a string containing $
expansions
of construction variable names.
As a simple example,
the example from the previous
section that used
env['CC']
to fetch the value of $CC
could also be written as:
env = Environment() print("CC is: %s"%env.subst('$CC'))
One advantage of using
subst
to expand strings is
that construction variables
in the result get re-expanded until
there are no expansions left in the string.
So a simple fetch of a value like
$CCCOM
:
env = Environment(CCFLAGS = '-DFOO') print("CCCOM is: %s"%env['CCCOM'])
Will print the unexpanded value of $CCCOM
,
showing us the construction
variables that still need to be expanded:
% scons -Q
CCCOM is: $CC $CCFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES
scons: `.' is up to date.
Calling the subst
method on $CCOM
,
however:
env = Environment(CCFLAGS = '-DFOO') print("CCCOM is: %s"%env.subst('$CCCOM'))
Will recursively expand all of
the construction variables prefixed
with $
(dollar signs),
showing us the final output:
% scons -Q
CCCOM is: gcc -DFOO -c -o
scons: `.' is up to date.
Note that because we're not expanding this
in the context of building something
there are no target or source files
for $TARGET
and $SOURCES
to expand.
If a problem occurs when expanding a construction variable,
by default it is expanded to ''
(a null string), and will not cause scons to fail.
env = Environment() print("value is: %s"%env.subst( '->$MISSING<-' ))
% scons -Q
value is: -><-
scons: `.' is up to date.
This default behaviour can be changed using the AllowSubstExceptions
function.
When a problem occurs with a variable expansion it generates
an exception, and the AllowSubstExceptions
function controls
which of these exceptions are actually fatal and which are
allowed to occur safely. By default, NameError
and IndexError
are the two exceptions that are allowed to occur: so instead of
causing scons to fail, these are caught, the variable expanded to
''
and scons execution continues.
To require that all construction variable names exist, and that
indexes out of range are not allowed, call AllowSubstExceptions
with no extra arguments.
AllowSubstExceptions() env = Environment() print("value is: %s"%env.subst( '->$MISSING<-' ))
% scons -Q
scons: *** NameError `MISSING' trying to evaluate `$MISSING'
File "/home/my/project/SConstruct", line 3, in <module>
This can also be used to allow other exceptions that might occur,
most usefully with the ${...}
construction
variable syntax. For example, this would allow zero-division to
occur in a variable expansion in addition to the default exceptions
allowed
AllowSubstExceptions(IndexError, NameError, ZeroDivisionError) env = Environment() print("value is: %s"%env.subst( '->${1 / 0}<-' ))
% scons -Q
value is: -><-
scons: `.' is up to date.
If AllowSubstExceptions
is called multiple times, each call
completely overwrites the previous list of allowed exceptions.
All of the Builder
functions that we've introduced so far,
like Program
and Library
,
actually use a default construction environment
that contains settings
for the various compilers
and other tools that
SCons configures by default,
or otherwise knows about
and has discovered on your system.
The goal of the default construction environment
is to make many configurations to "just work"
to build software using
readily available tools
with a minimum of configuration changes.
You can, however, control the settings
in the default construction environment
by using the DefaultEnvironment
function
to initialize various settings:
DefaultEnvironment(CC = '/usr/local/bin/gcc')
When configured as above,
all calls to the Program
or Object
Builder
will build object files with the
/usr/local/bin/gcc
compiler.
Note that the DefaultEnvironment
function
returns the initialized
default construction environment object,
which can then be manipulated like any
other construction environment.
So the following
would be equivalent to the
previous example,
setting the $CC
variable to /usr/local/bin/gcc
but as a separate step after
the default construction environment has been initialized:
env = DefaultEnvironment() env['CC'] = '/usr/local/bin/gcc'
One very common use of the DefaultEnvironment
function
is to speed up SCons initialization.
As part of trying to make most default
configurations "just work,"
SCons will actually
search the local system for installed
compilers and other utilities.
This search can take time,
especially on systems with
slow or networked file systems.
If you know which compiler(s) and/or
other utilities you want to configure,
you can control the search
that SCons performs
by specifying some specific
tool modules with which to
initialize the default construction environment:
env = DefaultEnvironment(tools = ['gcc', 'gnulink'], CC = '/usr/local/bin/gcc')
So the above example would tell SCons
to explicitly configure the default environment
to use its normal GNU Compiler and GNU Linker settings
(without having to search for them,
or any other utilities for that matter),
and specifically to use the compiler found at
/usr/local/bin/gcc
.
The real advantage of construction environments
is that you can create as many different construction
environments as you need,
each tailored to a different way to build
some piece of software or other file.
If, for example, we need to build
one program with the -O2
flag
and another with the -g
(debug) flag,
we would do this like so:
opt = Environment(CCFLAGS = '-O2') dbg = Environment(CCFLAGS = '-g') opt.Program('foo', 'foo.c') dbg.Program('bar', 'bar.c')
% scons -Q
cc -o bar.o -c -g bar.c
cc -o bar bar.o
cc -o foo.o -c -O2 foo.c
cc -o foo foo.o
We can even use multiple construction environments to build
multiple versions of a single program.
If you do this by simply trying to use the
Program
builder with both environments, though,
like this:
opt = Environment(CCFLAGS = '-O2') dbg = Environment(CCFLAGS = '-g') opt.Program('foo', 'foo.c') dbg.Program('foo', 'foo.c')
Then SCons generates the following error:
% scons -Q
scons: *** Two environments with different actions were specified for the same target: foo.o
File "/home/my/project/SConstruct", line 6, in <module>
This is because the two Program
calls have
each implicitly told SCons to generate an object file named
foo.o
,
one with a $CCFLAGS
value of
-O2
and one with a $CCFLAGS
value of
-g
.
SCons can't just decide that one of them
should take precedence over the other,
so it generates the error.
To avoid this problem,
we must explicitly specify
that each environment compile
foo.c
to a separately-named object file
using the Object
builder, like so:
opt = Environment(CCFLAGS = '-O2') dbg = Environment(CCFLAGS = '-g') o = opt.Object('foo-opt', 'foo.c') opt.Program(o) d = dbg.Object('foo-dbg', 'foo.c') dbg.Program(d)
Notice that each call to the Object
builder
returns a value,
an internal SCons object that
represents the object file that will be built.
We then use that object
as input to the Program
builder.
This avoids having to specify explicitly
the object file name in multiple places,
and makes for a compact, readable
SConstruct
file.
Our SCons output then looks like:
% scons -Q
cc -o foo-dbg.o -c -g foo.c
cc -o foo-dbg foo-dbg.o
cc -o foo-opt.o -c -O2 foo.c
cc -o foo-opt foo-opt.o
Sometimes you want more than one construction environment
to share the same values for one or more variables.
Rather than always having to repeat all of the common
variables when you create each construction environment,
you can use the Clone
method
to create a copy of a construction environment.
Like the Environment
call that creates a construction environment,
the Clone
method takes construction variable
assignments,
which will override the values in the copied construction environment.
For example, suppose we want to use gcc
to create three versions of a program,
one optimized, one debug, and one with neither.
We could do this by creating a "base" construction environment
that sets $CC
to gcc,
and then creating two copies,
one which sets $CCFLAGS
for optimization
and the other which sets $CCFLAGS
for debugging:
env = Environment(CC = 'gcc') opt = env.Clone(CCFLAGS = '-O2') dbg = env.Clone(CCFLAGS = '-g') env.Program('foo', 'foo.c') o = opt.Object('foo-opt', 'foo.c') opt.Program(o) d = dbg.Object('foo-dbg', 'foo.c') dbg.Program(d)
Then our output would look like:
% scons -Q
gcc -o foo.o -c foo.c
gcc -o foo foo.o
gcc -o foo-dbg.o -c -g foo.c
gcc -o foo-dbg foo-dbg.o
gcc -o foo-opt.o -c -O2 foo.c
gcc -o foo-opt foo-opt.o
You can replace existing construction variable values
using the Replace
method:
env = Environment(CCFLAGS = '-DDEFINE1') env.Replace(CCFLAGS = '-DDEFINE2') env.Program('foo.c')
The replacing value
(-DDEFINE2
in the above example)
completely replaces the value in the
construction environment:
% scons -Q
cc -o foo.o -c -DDEFINE2 foo.c
cc -o foo foo.o
You can safely call Replace
for construction variables that
don't exist in the construction environment:
env = Environment() env.Replace(NEW_VARIABLE = 'xyzzy') print("NEW_VARIABLE = %s"%env['NEW_VARIABLE'])
In this case, the construction variable simply gets added to the construction environment:
% scons -Q
NEW_VARIABLE = xyzzy
scons: `.' is up to date.
Because the variables aren't expanded until the construction environment is actually used to build the targets, and because SCons function and method calls are order-independent, the last replacement "wins" and is used to build all targets, regardless of the order in which the calls to Replace() are interspersed with calls to builder methods:
env = Environment(CCFLAGS = '-DDEFINE1') print("CCFLAGS = %s"%env['CCFLAGS']) env.Program('foo.c') env.Replace(CCFLAGS = '-DDEFINE2') print("CCFLAGS = %s"%env['CCFLAGS']) env.Program('bar.c')
The timing of when the replacement
actually occurs relative
to when the targets get built
becomes apparent
if we run scons
without the -Q
option:
% scons
scons: Reading SConscript files ...
CCFLAGS = -DDEFINE1
CCFLAGS = -DDEFINE2
scons: done reading SConscript files.
scons: Building targets ...
cc -o bar.o -c -DDEFINE2 bar.c
cc -o bar bar.o
cc -o foo.o -c -DDEFINE2 foo.c
cc -o foo foo.o
scons: done building targets.
Because the replacement occurs while
the SConscript
files are being read,
the $CCFLAGS
variable has already been set to
-DDEFINE2
by the time the foo.o
target is built,
even though the call to the Replace
method does not occur until later in
the SConscript
file.
Sometimes it's useful to be able to specify
that a construction variable should be
set to a value only if the construction environment
does not already have that variable defined
You can do this with the SetDefault
method,
which behaves similarly to the set_default
method of Python dictionary objects:
env.SetDefault(SPECIAL_FLAG = '-extra-option')
This is especially useful
when writing your own Tool
modules
to apply variables to construction environments.
You can append a value to
an existing construction variable
using the Append
method:
env = Environment(CCFLAGS = ['-DMY_VALUE']) env.Append(CCFLAGS = ['-DLAST']) env.Program('foo.c')
SCons then supplies both the -DMY_VALUE
and
-DLAST
flags when compiling the object file:
% scons -Q
cc -o foo.o -c -DMY_VALUE -DLAST foo.c
cc -o foo foo.o
If the construction variable doesn't already exist,
the Append
method will create it:
env = Environment() env.Append(NEW_VARIABLE = 'added') print("NEW_VARIABLE = %s"%env['NEW_VARIABLE'])
Which yields:
% scons -Q
NEW_VARIABLE = added
scons: `.' is up to date.
Note that the Append
function tries to be "smart"
about how the new value is appended to the old value.
If both are strings, the previous and new strings
are simply concatenated.
Similarly, if both are lists,
the lists are concatenated.
If, however, one is a string and the other is a list,
the string is added as a new element to the list.
Some times it's useful to add a new value
only if the existing construction variable
doesn't already contain the value.
This can be done using the AppendUnique
method:
env.AppendUnique(CCFLAGS=['-g'])
In the above example,
the -g
would be added
only if the $CCFLAGS
variable
does not already contain a -g
value.
You can append a value to the beginning of
an existing construction variable
using the Prepend
method:
env = Environment(CCFLAGS = ['-DMY_VALUE']) env.Prepend(CCFLAGS = ['-DFIRST']) env.Program('foo.c')
SCons then supplies both the -DFIRST
and
-DMY_VALUE
flags when compiling the object file:
% scons -Q
cc -o foo.o -c -DFIRST -DMY_VALUE foo.c
cc -o foo foo.o
If the construction variable doesn't already exist,
the Prepend
method will create it:
env = Environment() env.Prepend(NEW_VARIABLE = 'added') print("NEW_VARIABLE = %s"%env['NEW_VARIABLE'])
Which yields:
% scons -Q
NEW_VARIABLE = added
scons: `.' is up to date.
Like the Append
function,
the Prepend
function tries to be "smart"
about how the new value is appended to the old value.
If both are strings, the previous and new strings
are simply concatenated.
Similarly, if both are lists,
the lists are concatenated.
If, however, one is a string and the other is a list,
the string is added as a new element to the list.
Some times it's useful to add a new value
to the beginning of a construction variable
only if the existing value
doesn't already contain the to-be-added value.
This can be done using the PrependUnique
method:
env.PrependUnique(CCFLAGS=['-g'])
In the above example,
the -g
would be added
only if the $CCFLAGS
variable
does not already contain a -g
value.
When SCons builds a target file,
it does not execute the commands with
the same external environment
that you used to execute SCons.
Instead, it uses the dictionary
stored in the $ENV
construction variable
as the external environment
for executing commands.
The most important ramification of this behavior
is that the PATH
environment variable,
which controls where the operating system
will look for commands and utilities,
is not the same as in the external environment
from which you called SCons.
This means that SCons will not, by default,
necessarily find all of the tools
that you can execute from the command line.
The default value of the PATH
environment variable
on a POSIX system
is /usr/local/bin:/bin:/usr/bin
.
The default value of the PATH
environment variable
on a Windows system comes from the Windows registry
value for the command interpreter.
If you want to execute any commands--compilers, linkers, etc.--that
are not in these default locations,
you need to set the PATH
value
in the $ENV
dictionary
in your construction environment.
The simplest way to do this is to initialize explicitly the value when you create the construction environment; this is one way to do that:
path = ['/usr/local/bin', '/bin', '/usr/bin'] env = Environment(ENV = {'PATH' : path})
Assign a dictionary to the $ENV
construction variable in this way
completely resets the external environment
so that the only variable that will be
set when external commands are executed
will be the PATH
value.
If you want to use the rest of
the values in $ENV
and only
set the value of PATH
,
the most straightforward way is probably:
env['ENV']['PATH'] = ['/usr/local/bin', '/bin', '/usr/bin']
Note that SCons does allow you to define
the directories in the PATH
in a string,
separated by the pathname-separator character
for your system (':' on POSIX systems, ';' on Windows):
env['ENV']['PATH'] = '/usr/local/bin:/bin:/usr/bin'
But doing so makes your SConscript
file less portable,
(although in this case that may not be a huge concern
since the directories you list are likley system-specific, anyway).
You may want to propagate the external PATH
to the execution environment for commands.
You do this by initializing the PATH
variable with the PATH
value from
the os.environ
dictionary,
which is Python's way of letting you
get at the external environment:
import os env = Environment(ENV = {'PATH' : os.environ['PATH']})
Alternatively, you may find it easier
to just propagate the entire external
environment to the execution environment
for commands.
This is simpler to code than explicity
selecting the PATH
value:
import os env = Environment(ENV = os.environ)
Either of these will guarantee that
SCons will be able to execute
any command that you can execute from the command line.
The drawback is that the build can behave
differently if it's run by people with
different PATH
values in their environment--for example,
if both the /bin
and
/usr/local/bin
directories
have different cc commands,
then which one will be used to compile programs
will depend on which directory is listed
first in the user's PATH
variable.
One of the most common requirements
for manipulating a variable in the execution environment
is to add one or more custom directories to a search
like the $PATH
variable on Linux or POSIX systems,
or the %PATH%
variable on Windows,
so that a locally-installed compiler or other utility
can be found when SCons tries to execute it to update a target.
SCons provides PrependENVPath
and AppendENVPath
functions
to make adding things to execution variables convenient.
You call these functions by specifying the variable
to which you want the value added,
and then value itself.
So to add some /usr/local
directories
to the $PATH
and $LIB
variables,
you might:
env = Environment(ENV = os.environ) env.PrependENVPath('PATH', '/usr/local/bin') env.AppendENVPath('LIB', '/usr/local/lib')
Note that the added values are strings,
and if you want to add multiple directories to
a variable like $PATH
,
you must include the path separate character
(:
on Linux or POSIX,
;
on Windows)
in the string.
Normally when using a tool from the construction environment,
several different search locations are checked by default.
This includes the Scons/Tools/
directory
inbuilt to scons and the directory site_scons/site_tools
relative to the root SConstruct file.
# Builtin tool or tool located within site_tools env = Environment(tools = ['SomeTool']) env.SomeTool(targets, sources) # The search locations would include by default SCons/Tool/SomeTool.py SCons/Tool/SomeTool/__init__.py ./site_scons/site_tools/SomeTool.py ./site_scons/site_tools/SomeTool/__init__.py
In some cases you may want to specify a different location to search for tools. The Environment constructor contains an option for this called toolpath This can be used to add additional search directories.
# Tool located within the toolpath directory option env = Environment(tools = ['SomeTool'], toolpath = ['/opt/SomeToolPath', '/opt/SomeToolPath2']) env.SomeTool(targets, sources) # The search locations in this example would include: /opt/SomeToolPath/SomeTool.py /opt/SomeToolPath/SomeTool/__init__.py /opt/SomeToolPath2/SomeTool.py /opt/SomeToolPath2/SomeTool/__init__.py SCons/Tool/SomeTool.py SCons/Tool/SomeTool/__init__.py ./site_scons/site_tools/SomeTool.py ./site_scons/site_tools/SomeTool/__init__.py
SCons 3.0 now supports the ability for a Builder to be located within a sub-directory / sub-package of the toolpath. This is similar to namespacing within python. With nested or namespaced tools we can use the dot notation to specify a sub-directory that the tool is located under.
# namespaced target env = Environment(tools = ['SubDir1.SubDir2.SomeTool'], toolpath = ['/opt/SomeToolPath']) env.SomeTool(targets, sources) # With this example the search locations would include /opt/SomeToolPath/SubDir1/SubDir2/SomeTool.py /opt/SomeToolPath/SubDir1/SubDir2/SomeTool/__init__.py SCons/Tool/SubDir1/SubDir2/SomeTool.py SCons/Tool/SubDir1/SubDir2/SomeTool/__init__.py ./site_scons/site_tools/SubDir1/SubDir2/SomeTool.py ./site_scons/site_tools/SubDir1/SubDir2/SomeTool/__init__.py
For python2 It's important to note when creating tools within sub-directories, there needs to be a __init__.py file within each directory. This file can just be empty. This is the same constraint used by python when loading modules from within sub-directories (packages). For python3 this appears to be no longer a requirement.
If we want to access tools externally to scons on the sys.path (one example would be tools installed via the pip package manager) One way to do this is to use sys.path with the toolpath. One thing to watch out for with this approach is that sys.path can sometimes contains paths to .egg files instead of directories. So we need to filter those out with this approach.
# namespaced target using sys.path within toolpath searchpaths = [] for item in sys.path: if os.path.isdir(item): searchpaths.append(item) env = Environment(tools = ['someinstalledpackage.SomeTool'], toolpath = searchpaths) env.SomeTool(targets, sources)
By using sys.path with the toolpath argument and by using the nested syntax we can have scons search packages installed via pip for Tools.
# For Windows based on the python version and install directory, this may be something like C:\Python35\Lib\site-packages\someinstalledpackage\SomeTool.py C:\Python35\Lib\site-packages\someinstalledpackage\SomeTool\__init__.py # For Linux this could be something like: /usr/lib/python3/dist-packages/someinstalledpackage/SomeTool.py /usr/lib/python3/dist-packages/someinstalledpackage/SomeTool/__init__.py
In some cases you may want to use a tool located within a installed external pip package. This is possible by the use of sys.path with the toolpath. However in that situation you need to provide a prefix to the toolname to indicate where it is located within sys.path
searchpaths = [] for item in sys.path: if os.path.isdir(item): searchpaths.append(item) env = Environment(tools = ['tools_example.subdir1.subdir2.SomeTool'], toolpath = searchpaths) env.SomeTool(targets, sources)
To avoid the use of a prefix within the name of the tool or filtering sys.path for directories,
we can use the PyPackageDir(modulename)
function to locate the directory of the python package.
PyPackageDir
returns a Dir object which represents the path of the directory
for the python package / module specified as a parameter.
# namespaced target using sys.path env = Environment(tools = ['SomeTool'], toolpath = [PyPackageDir('tools_example.subdir1.subdir2')]) env.SomeTool(targets, sources)
This chapter describes the MergeFlags
, ParseFlags
, and ParseConfig
methods of a construction environment
.
SCons construction environments have a MergeFlags
method
that merges a dictionary of values into the construction environment.
MergeFlags
treats each value in the dictionary
as a list of options such as one might pass to a command
(such as a compiler or linker).
MergeFlags
will not duplicate an option
if it already exists in the construction environment variable.
MergeFlags
tries to be intelligent about merging options.
When merging options to any variable
whose name ends in PATH
,
MergeFlags
keeps the leftmost occurrence of the option,
because in typical lists of directory paths,
the first occurrence "wins."
When merging options to any other variable name,
MergeFlags
keeps the rightmost occurrence of the option,
because in a list of typical command-line options,
the last occurrence "wins."
env = Environment() env.Append(CCFLAGS = '-option -O3 -O1') flags = { 'CCFLAGS' : '-whatever -O3' } env.MergeFlags(flags) print env['CCFLAGS']
% scons -Q
['-option', '-O1', '-whatever', '-O3']
scons: `.' is up to date.
Note that the default value for $CCFLAGS
is an internal SCons object
which automatically converts
the options we specified as a string into a list.
env = Environment() env.Append(CPPPATH = ['/include', '/usr/local/include', '/usr/include']) flags = { 'CPPPATH' : ['/usr/opt/include', '/usr/local/include'] } env.MergeFlags(flags) print env['CPPPATH']
% scons -Q
['/include', '/usr/local/include', '/usr/include', '/usr/opt/include']
scons: `.' is up to date.
Note that the default value for $CPPPATH
is a normal Python list,
so we must specify its values as a list
in the dictionary we pass to the MergeFlags
function.
If MergeFlags
is passed anything other than a dictionary,
it calls the ParseFlags
method to convert it into a dictionary.
env = Environment() env.Append(CCFLAGS = '-option -O3 -O1') env.Append(CPPPATH = ['/include', '/usr/local/include', '/usr/include']) env.MergeFlags('-whatever -I/usr/opt/include -O3 -I/usr/local/include') print env['CCFLAGS'] print env['CPPPATH']
% scons -Q
['-option', '-O1', '-whatever', '-O3']
['/include', '/usr/local/include', '/usr/include', '/usr/opt/include']
scons: `.' is up to date.
In the combined example above,
ParseFlags
has sorted the options into their corresponding variables
and returned a dictionary for MergeFlags
to apply
to the construction variables
in the specified construction environment.
SCons has a bewildering array of construction variables for different types of options when building programs. Sometimes you may not know exactly which variable should be used for a particular option.
SCons construction environments have a ParseFlags
method
that takes a set of typical command-line options
and distrbutes them into the appropriate construction variables.
Historically, it was created to support the ParseConfig
method,
so it focuses on options used by the GNU Compiler Collection (GCC)
for the C and C++ toolchains.
ParseFlags
returns a dictionary containing the options
distributed into their respective construction variables.
Normally, this dictionary would be passed to MergeFlags
to merge the options into a construction environment
,
but the dictionary can be edited if desired to provide
additional functionality.
(Note that if the flags are not going to be edited,
calling MergeFlags
with the options directly
will avoid an additional step.)
env = Environment() d = env.ParseFlags("-I/opt/include -L/opt/lib -lfoo") for k,v in sorted(d.items()): if v: print k, v env.MergeFlags(d) env.Program('f1.c')
% scons -Q
CPPPATH ['/opt/include']
LIBPATH ['/opt/lib']
LIBS ['foo']
cc -o f1.o -c -I/opt/include f1.c
cc -o f1 f1.o -L/opt/lib -lfoo
Note that if the options are limited to generic types like those above, they will be correctly translated for other platform types:
C:\>scons -Q
CPPPATH ['/opt/include']
LIBPATH ['/opt/lib']
LIBS ['foo']
cl /Fof1.obj /c f1.c /nologo /I\opt\include
link /nologo /OUT:f1.exe /LIBPATH:\opt\lib foo.lib f1.obj
embedManifestExeCheck(target, source, env)
Since the assumption is that the flags are used for the GCC toolchain,
unrecognized flags are placed in $CCFLAGS
so they will be used for both C and C++ compiles:
env = Environment() d = env.ParseFlags("-whatever") for k,v in sorted(d.items()): if v: print k, v env.MergeFlags(d) env.Program('f1.c')
% scons -Q
CCFLAGS -whatever
cc -o f1.o -c -whatever f1.c
cc -o f1 f1.o
ParseFlags
will also accept a (recursive) list of strings as input;
the list is flattened before the strings are processed:
env = Environment() d = env.ParseFlags(["-I/opt/include", ["-L/opt/lib", "-lfoo"]]) for k,v in sorted(d.items()): if v: print k, v env.MergeFlags(d) env.Program('f1.c')
% scons -Q
CPPPATH ['/opt/include']
LIBPATH ['/opt/lib']
LIBS ['foo']
cc -o f1.o -c -I/opt/include f1.c
cc -o f1 f1.o -L/opt/lib -lfoo
If a string begins with a "!" (an exclamation mark, often called a bang), the string is passed to the shell for execution. The output of the command is then parsed:
env = Environment() d = env.ParseFlags(["!echo -I/opt/include", "!echo -L/opt/lib", "-lfoo"]) for k,v in sorted(d.items()): if v: print k, v env.MergeFlags(d) env.Program('f1.c')
% scons -Q
CPPPATH ['/opt/include']
LIBPATH ['/opt/lib']
LIBS ['foo']
cc -o f1.o -c -I/opt/include f1.c
cc -o f1 f1.o -L/opt/lib -lfoo
ParseFlags
is regularly updated for new options;
consult the man page for details about those currently recognized.
Configuring the right options to build programs to work with
libraries--especially shared libraries--that are available
on POSIX systems can be very complicated.
To help this situation,
various utilies with names that end in config
return the command-line options for the GNU Compiler Collection (GCC)
that are needed to use these libraries;
for example, the command-line options
to use a library named lib
would be found by calling a utility named lib-config
.
A more recent convention is that these options
are available from the generic pkg-config
program,
which has common framework, error handling, and the like,
so that all the package creator has to do is provide the set of strings
for his particular package.
SCons construction environments have a ParseConfig
method
that executes a *config
utility
(either pkg-config
or a
more specific utility)
and configures the appropriate construction variables
in the environment
based on the command-line options
returned by the specified command.
env = Environment() env['CPPPATH'] = ['/lib/compat'] env.ParseConfig("pkg-config x11 --cflags --libs") print env['CPPPATH']
SCons will execute the specified command string, parse the resultant flags, and add the flags to the appropriate environment variables.
% scons -Q
['/lib/compat', '/usr/X11/include']
scons: `.' is up to date.
In the example above, SCons has added the include directory to
CPPPATH
.
(Depending upon what other flags are emitted by the
pkg-config
command,
other variables may have been extended as well.)
Note that the options are merged with existing options using
the MergeFlags
method,
so that each option only occurs once in the construction variable:
env = Environment() env.ParseConfig("pkg-config x11 --cflags --libs") env.ParseConfig("pkg-config x11 --cflags --libs") print env['CPPPATH']
% scons -Q
['/usr/X11/include']
scons: `.' is up to date.
A key aspect of creating a usable build configuration is providing good output from the build so its users can readily understand what the build is doing and get information about how to control the build. SCons provides several ways of controlling output from the build configuration to help make the build more useful and understandable.
It's often very useful to be able to give
users some help that describes the
specific targets, build options, etc.,
that can be used for your build.
SCons provides the Help
function
to allow you to specify this help text:
Help(""" Type: 'scons program' to build the production program, 'scons debug' to build the debug version. """)
Optionally, one can specify the append flag:
Help(""" Type: 'scons program' to build the production program, 'scons debug' to build the debug version. """, append=True)
(Note the above use of the Python triple-quote syntax, which comes in very handy for specifying multi-line strings like help text.)
When the SConstruct
or SConscript
files
contain such a call to the Help
function,
the specified help text will be displayed in response to
the SCons -h
option:
% scons -h
scons: Reading SConscript files ...
scons: done reading SConscript files.
Type: 'scons program' to build the production program,
'scons debug' to build the debug version.
Use scons -H for help about command-line options.
The SConscript
files may contain
multiple calls to the Help
function,
in which case the specified text(s)
will be concatenated when displayed.
This allows you to split up the
help text across multiple SConscript
files.
In this situation, the order in
which the SConscript
files are called
will determine the order in which the Help
functions are called,
which will determine the order in which
the various bits of text will get concatenated.
When used with AddOption
Help("text", append=False) will clobber any help output associated with AddOption().
To preserve the help output from AddOption(), set append=True.
Another use would be to make the help text conditional
on some variable.
For example, suppose you only want to display
a line about building a Windows-only
version of a program when actually
run on Windows.
The following SConstruct
file:
env = Environment() Help("\nType: 'scons program' to build the production program.\n") if env['PLATFORM'] == 'win32': Help("\nType: 'scons windebug' to build the Windows debug version.\n")
Will display the complete help text on Windows:
C:\>scons -h
scons: Reading SConscript files ...
scons: done reading SConscript files.
Type: 'scons program' to build the production program.
Type: 'scons windebug' to build the Windows debug version.
Use scons -H for help about command-line options.
But only show the relevant option on a Linux or UNIX system:
% scons -h
scons: Reading SConscript files ...
scons: done reading SConscript files.
Type: 'scons program' to build the production program.
Use scons -H for help about command-line options.
If there is no Help
text in the SConstruct
or
SConscript
files,
SCons will revert to displaying its
standard list that describes the SCons command-line
options.
This list is also always displayed whenever
the -H
option is used.
Sometimes the commands executed
to compile object files or link programs
(or build other targets)
can get very long,
long enough to make it difficult for users
to distinguish error messages or
other important build output
from the commands themselves.
All of the default $*COM
variables
that specify the command lines
used to build various types of target files
have a corresponding $*COMSTR
variable
that can be set to an alternative
string that will be displayed
when the target is built.
For example, suppose you want to
have SCons display a
"Compiling"
message whenever it's compiling an object file,
and a
"Linking"
when it's linking an executable.
You could write a SConstruct
file
that looks like:
env = Environment(CCCOMSTR = "Compiling $TARGET", LINKCOMSTR = "Linking $TARGET") env.Program('foo.c')
Which would then yield the output:
% scons -Q
Compiling foo.o
Linking foo
SCons performs complete variable substitution
on $*COMSTR
variables,
so they have access to all of the
standard variables like $TARGET
$SOURCES
, etc.,
as well as any construction variables
that happen to be configured in
the construction environment
used to build a specific target.
Of course, sometimes it's still important to be able to see the exact command that SCons will execute to build a target. For example, you may simply need to verify that SCons is configured to supply the right options to the compiler, or a developer may want to cut-and-paste a compile command to add a few options for a custom test.
One common way to give users
control over whether or not
SCons should print the actual command line
or a short, configured summary
is to add support for a
VERBOSE
command-line variable to your SConstruct
file.
A simple configuration for this might look like:
env = Environment() if ARGUMENTS.get('VERBOSE') != "1': env['CCCOMSTR'] = "Compiling $TARGET" env['LINKCOMSTR'] = "Linking $TARGET" env.Program('foo.c')
By only setting the appropriate
$*COMSTR
variables
if the user specifies
VERBOSE=1
on the command line,
the user has control
over how SCons
displays these particular command lines:
%scons -Q
Compiling foo.o Linking foo %scons -Q -c
Removed foo.o Removed foo %scons -Q VERBOSE=1
cc -o foo.o -c foo.c cc -o foo foo.o
Another aspect of providing good build output is to give the user feedback about what SCons is doing even when nothing is being built at the moment. This can be especially true for large builds when most of the targets are already up-to-date. Because SCons can take a long time making absolutely sure that every target is, in fact, up-to-date with respect to a lot of dependency files, it can be easy for users to mistakenly conclude that SCons is hung or that there is some other problem with the build.
One way to deal with this perception
is to configure SCons to print something to
let the user know what it's "thinking about."
The Progress
function
allows you to specify a string
that will be printed for every file
that SCons is "considering"
while it is traversing the dependency graph
to decide what targets are or are not up-to-date.
Progress('Evaluating $TARGET\n') Program('f1.c') Program('f2.c')
Note that the Progress
function does not
arrange for a newline to be printed automatically
at the end of the string (as does the Python
print
statement),
and we must specify the
\n
that we want printed at the end of the configured string.
This configuration, then,
will have SCons
print that it is Evaluating
each file that it encounters
in turn as it traverses the dependency graph:
% scons -Q
Evaluating SConstruct
Evaluating f1.c
Evaluating f1.o
cc -o f1.o -c f1.c
Evaluating f1
cc -o f1 f1.o
Evaluating f2.c
Evaluating f2.o
cc -o f2.o -c f2.c
Evaluating f2
cc -o f2 f2.o
Evaluating .
Of course, normally you don't want to add
all of these additional lines to your build output,
as that can make it difficult for the user
to find errors or other important messages.
A more useful way to display
this progress might be
to have the file names printed
directly to the user's screen,
not to the same standard output
stream where build output is printed,
and to use a carriage return character
(\r
)
so that each file name gets re-printed on the same line.
Such a configuration would look like:
Progress('$TARGET\r', file=open('/dev/tty', 'w'), overwrite=True) Program('f1.c') Program('f2.c')
Note that we also specified the
overwrite=True
argument
to the Progress
function,
which causes SCons to
"wipe out" the previous string with space characters
before printing the next Progress
string.
Without the
overwrite=True
argument,
a shorter file name would not overwrite
all of the charactes in a longer file name that
precedes it,
making it difficult to tell what the
actual file name is on the output.
Also note that we opened up the
/dev/tty
file
for direct access (on POSIX) to
the user's screen.
On Windows, the equivalent would be to open
the con:
file name.
Also, it's important to know that although you can use
$TARGET
to substitute the name of
the node in the string,
the Progress
function does not
perform general variable substitution
(because there's not necessarily a construction
environment involved in evaluating a node
like a source file, for example).
You can also specify a list of strings
to the Progress
function,
in which case SCons will
display each string in turn.
This can be used to implement a "spinner"
by having SCons cycle through a
sequence of strings:
Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5) Program('f1.c') Program('f2.c')
Note that here we have also used the
interval=
keyword argument to have SCons
only print a new "spinner" string
once every five evaluated nodes.
Using an interval=
count,
even with strings that use $TARGET
like
our examples above,
can be a good way to lessen the
work that SCons expends printing Progress
strings,
while still giving the user feedback
that indicates SCons is still
working on evaluating the build.
Lastly, you can have direct control
over how to print each evaluated node
by passing a Python function
(or other Python callable)
to the Progress
function.
Your function will be called
for each evaluated node,
allowing you to
implement more sophisticated logic
like adding a counter:
screen = open('/dev/tty', 'w') count = 0 def progress_function(node) count += 1 screen.write('Node %4d: %s\r' % (count, node)) Progress(progress_function)
Of course, if you choose,
you could completely ignore the
node
argument to the function,
and just print a count,
or anything else you wish.
(Note that there's an obvious follow-on question here: how would you find the total number of nodes that will be evaluated so you can tell the user how close the build is to finishing? Unfortunately, in the general case, there isn't a good way to do that, short of having SCons evaluate its dependency graph twice, first to count the total and the second time to actually build the targets. This would be necessary because you can't know in advance which target(s) the user actually requested to be built. The entire build may consist of thousands of Nodes, for example, but maybe the user specifically requested that only a single object file be built.)
SCons, like most build tools, returns zero status to the shell on success and nonzero status on failure. Sometimes it's useful to give more information about the build status at the end of the run, for instance to print an informative message, send an email, or page the poor slob who broke the build.
SCons provides a GetBuildFailures
method that
you can use in a python atexit
function
to get a list of objects describing the actions that failed
while attempting to build targets. There can be more
than one if you're using -j
. Here's a
simple example:
import atexit def print_build_failures(): from SCons.Script import GetBuildFailures for bf in GetBuildFailures(): print("%s failed: %s" % (bf.node, bf.errstr)) atexit.register(print_build_failures)
The atexit.register
call
registers print_build_failures
as an atexit
callback, to be called
before SCons exits. When that function is called,
it calls GetBuildFailures
to fetch the list of failed objects.
See the man page
for the detailed contents of the returned objects;
some of the more useful attributes are
.node
,
.errstr
,
.filename
, and
.command
.
The filename
is not necessarily
the same file as the node
; the
node
is the target that was
being built when the error occurred, while the
filename
is the file or dir that
actually caused the error.
Note: only call GetBuildFailures
at the end of the
build; calling it at any other time is undefined.
Here is a more complete example showing how to
turn each element of GetBuildFailures
into a string:
# Make the build fail if we pass fail=1 on the command line if ARGUMENTS.get('fail', 0): Command('target', 'source', ['/bin/false']) def bf_to_str(bf): """Convert an element of GetBuildFailures() to a string in a useful way.""" import SCons.Errors if bf is None: # unknown targets product None in list return '(unknown tgt)' elif isinstance(bf, SCons.Errors.StopError): return str(bf) elif bf.node: return str(bf.node) + ': ' + bf.errstr elif bf.filename: return bf.filename + ': ' + bf.errstr return 'unknown failure: ' + bf.errstr import atexit def build_status(): """Convert the build status to a 2-tuple, (status, msg).""" from SCons.Script import GetBuildFailures bf = GetBuildFailures() if bf: # bf is normally a list of build failures; if an element is None, # it's because of a target that scons doesn't know anything about. status = 'failed' failures_message = "\n".join(["Failed building %s" % bf_to_str(x) for x in bf if x is not None]) else: # if bf is None, the build completed successfully. status = 'ok' failures_message = '' return (status, failures_message) def display_build_status(): """Display the build status. Called by atexit. Here you could do all kinds of complicated things.""" status, failures_message = build_status() if status == 'failed': print("FAILED!!!!") # could display alert, ring bell, etc. elif status == 'ok': print("Build succeeded.") print(failures_message) atexit.register(display_build_status)
When this runs, you'll see the appropriate output:
%scons -Q
scons: `.' is up to date. Build succeeded. %scons -Q fail=1
scons: *** [target] Source `source' not found, needed by target `target'. FAILED!!!! Failed building target: Source `source' not found, needed by target `target'.
SCons provides a number of ways
for the writer of the SConscript
files
to give the users who will run SCons
a great deal of control over the build execution.
The arguments that the user can specify on
the command line are broken down into three types:
Command-line options always begin with
one or two -
(hyphen) characters.
SCons provides ways for you to examine
and set options values from within your SConscript
files,
as well as the ability to define your own
custom options.
See Section 10.1, “Command-Line Options”, below.
Any command-line argument containing an =
(equal sign) is considered a variable setting with the form
variable
=value
.
SCons provides direct access to
all of the command-line variable settings,
the ability to apply command-line variable settings
to construction environments,
and functions for configuring
specific types of variables
(Boolean values, path names, etc.)
with automatic validation of the user's specified values.
See Section 10.2, “Command-Line variable
=value
Build Variables”, below.
Any command-line argument that is not an option
or a variable setting
(does not begin with a hyphen
and does not contain an equal sign)
is considered a target that the user
(presumably) wants SCons to build.
A list of Node objects representing
the target or targets to build.
SCons provides access to the list of specified targets,
as well as ways to set the default list of targets
from within the SConscript
files.
See Section 10.3, “Command-Line Targets”, below.
SCons has many command-line options
that control its behavior.
A SCons command-line option
always begins with one or two -
(hyphen)
characters.
Users may find themselves supplying
the same command-line options every time
they run SCons.
For example, you might find it saves time
to specify a value of -j 2
to have SCons run up to two build commands in parallel.
To avoid having to type -j 2
by hand
every time,
you can set the external environment variable
SCONSFLAGS
to a string containing
command-line options that you want SCons to use.
If, for example,
you're using a POSIX shell that's
compatible with the Bourne shell,
and you always want SCons to use the
-Q
option,
you can set the SCONSFLAGS
environment as follows:
%scons
scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... ... [build output] ... scons: done building targets. %export SCONSFLAGS="-Q"
%scons
... [build output] ...
Users of csh-style shells on POSIX systems
can set the SCONSFLAGS
environment as follows:
$ setenv SCONSFLAGS "-Q"
Windows users may typically want to set the
SCONSFLAGS
in the appropriate tab of the
System Properties
window.
SCons provides the GetOption
function
to get the values set by the various command-line options.
One common use of this is to check whether or not
the -h
or --help
option
has been specified.
Normally, SCons does not print its help text
until after it has read all of the SConscript
files,
because it's possible that help text has been added
by some subsidiary SConscript
file deep in the
source tree hierarchy.
Of course, reading all of the SConscript
files
takes extra time.
If you know that your configuration does not define
any additional help text in subsidiary SConscript
files,
you can speed up the command-line help available to users
by using the GetOption
function to load the
subsidiary SConscript
files only if the
the user has not specified
the -h
or --help
option,
like so:
if not GetOption('help'): SConscript('src/SConscript', export='env')
In general, the string that you pass to the
GetOption
function to fetch the value of a command-line
option setting is the same as the "most common" long option name
(beginning with two hyphen characters),
although there are some exceptions.
The list of SCons command-line options
and the GetOption
strings for fetching them,
are available in the
Section 10.1.4, “Strings for Getting or Setting Values of SCons Command-Line Options” section,
below.
You can also set the values of SCons
command-line options from within the SConscript
files
by using the SetOption
function.
The strings that you use to set the values of SCons
command-line options are available in the
Section 10.1.4, “Strings for Getting or Setting Values of SCons Command-Line Options” section,
below.
One use of the SetOption
function is to
specify a value for the -j
or --jobs
option,
so that users get the improved performance
of a parallel build without having to specify the option by hand.
A complicating factor is that a good value
for the -j
option is
somewhat system-dependent.
One rough guideline is that the more processors
your system has,
the higher you want to set the
-j
value,
in order to take advantage of the number of CPUs.
For example, suppose the administrators
of your development systems
have standardized on setting a
NUM_CPU
environment variable
to the number of processors on each system.
A little bit of Python code
to access the environment variable
and the SetOption
function
provide the right level of flexibility:
import os num_cpu = int(os.environ.get('NUM_CPU', 2)) SetOption('num_jobs', num_cpu) print("running with -j %s"%GetOption('num_jobs'))
The above snippet of code
sets the value of the --jobs
option
to the value specified in the
$NUM_CPU
environment variable.
(This is one of the exception cases
where the string is spelled differently from
the from command-line option.
The string for fetching or setting the --jobs
value is num_jobs
for historical reasons.)
The code in this example prints the num_jobs
value for illustrative purposes.
It uses a default value of 2
to provide some minimal parallelism even on
single-processor systems:
% scons -Q
running with -j 2
scons: `.' is up to date.
But if the $NUM_CPU
environment variable is set,
then we use that for the default number of jobs:
%export NUM_CPU="4"
%scons -Q
running with -j 4 scons: `.' is up to date.
But any explicit
-j
or --jobs
value the user specifies an the command line is used first,
regardless of whether or not
the $NUM_CPU
environment
variable is set:
%scons -Q -j 7
running with -j 7 scons: `.' is up to date. %export NUM_CPU="4"
%scons -Q -j 3
running with -j 3 scons: `.' is up to date.
The strings that you can pass to the GetOption
and SetOption
functions usually correspond to the
first long-form option name
(beginning with two hyphen characters: --
),
after replacing any remaining hyphen characters
with underscores.
The full list of strings and the variables they correspond to is as follows:
String for GetOption and SetOption | Command-Line Option(s) |
---|---|
cache_debug | --cache-debug |
cache_disable | --cache-disable |
cache_force | --cache-force |
cache_show | --cache-show |
clean | -c ,
--clean ,
--remove |
config | --config |
directory | -C ,
--directory |
diskcheck | --diskcheck |
duplicate | --duplicate |
file | -f ,
--file ,
--makefile ,
--sconstruct |
help | -h ,
--help |
ignore_errors | --ignore-errors |
implicit_cache | --implicit-cache |
implicit_deps_changed | --implicit-deps-changed |
implicit_deps_unchanged | --implicit-deps-unchanged |
interactive | --interact ,
--interactive |
keep_going | -k ,
--keep-going |
max_drift | --max-drift |
no_exec | -n ,
--no-exec ,
--just-print ,
--dry-run ,
--recon |
no_site_dir | --no-site-dir |
num_jobs | -j ,
--jobs |
profile_file | --profile |
question | -q ,
--question |
random | --random |
repository | -Y ,
--repository ,
--srcdir |
silent | -s ,
--silent ,
--quiet |
site_dir | --site-dir |
stack_size | --stack-size |
taskmastertrace_file | --taskmastertrace |
warn | --warn --warning |
SCons also allows you to define your own
command-line options with the AddOption
function.
The AddOption
function takes the same arguments
as the optparse.add_option
function
from the standard Python library.
[3]
Once you have added a custom command-line option
with the AddOption
function,
the value of the option (if any) is immediately available
using the standard GetOption
function.
(The value can also be set using SetOption
,
although that's not very useful in practice
because a default value can be specified in
directly in the AddOption
call.)
One useful example of using this functionality
is to provide a --prefix
for users:
AddOption('--prefix', dest='prefix', type='string', nargs=1, action='store', metavar='DIR', help='installation prefix') env = Environment(PREFIX = GetOption('prefix')) installed_foo = env.Install('$PREFIX/usr/bin', 'foo.in') Default(installed_foo)
The above code uses the GetOption
function
to set the $PREFIX
construction variable to any
value that the user specifies with a command-line
option of --prefix
.
Because $PREFIX
will expand to a null string if it's not initialized,
running SCons without the
option of --prefix
will install the file in the
/usr/bin/
directory:
% scons -Q -n
Install file: "foo.in" as "/usr/bin/foo.in"
But specifying --prefix=/tmp/install
on the command line causes the file to be installed in the
/tmp/install/usr/bin/
directory:
% scons -Q -n --prefix=/tmp/install
Install file: "foo.in" as "/tmp/install/usr/bin/foo.in"
You may want to control various aspects
of your build by allowing the user
to specify variable
=value
values on the command line.
For example, suppose you
want users to be able to
build a debug version of a program
by running SCons as follows:
% scons -Q debug=1
SCons provides an ARGUMENTS
dictionary
that stores all of the
variable
=value
assignments from the command line.
This allows you to modify
aspects of your build in response
to specifications on the command line.
(Note that unless you want to require
that users always
specify a variable,
you probably want to use
the Python
ARGUMENTS.get()
function,
which allows you to specify a default value
to be used if there is no specification
on the command line.)
The following code sets the $CCFLAGS
construction
variable in response to the debug
flag being set in the ARGUMENTS
dictionary:
env = Environment() debug = ARGUMENTS.get('debug', 0) if int(debug): env.Append(CCFLAGS = '-g') env.Program('prog.c')
This results in the -g
compiler option being used when
debug=1
is used on the command line:
%scons -Q debug=0
cc -o prog.o -c prog.c cc -o prog prog.o %scons -Q debug=0
scons: `.' is up to date. %scons -Q debug=1
cc -o prog.o -c -g prog.c cc -o prog prog.o %scons -Q debug=1
scons: `.' is up to date.
Notice that SCons keeps track of
the last values used to build the object files,
and as a result correctly rebuilds
the object and executable files
only when the value of the debug
argument has changed.
The ARGUMENTS
dictionary has two minor drawbacks.
First, because it is a dictionary,
it can only store one value for each specified keyword,
and thus only "remembers" the last setting
for each keyword on the command line.
This makes the ARGUMENTS
dictionary
inappropriate if users should be able to
specify multiple values
on the command line for a given keyword.
Second, it does not preserve
the order in which the variable settings
were specified,
which is a problem if
you want the configuration to
behave differently in response
to the order in which the build
variable settings were specified on the command line.
To accomodate these requirements,
SCons provides an ARGLIST
variable
that gives you direct access to
variable
=value
settings on the command line,
in the exact order they were specified,
and without removing any duplicate settings.
Each element in the ARGLIST
variable
is itself a two-element list
containing the keyword and the value
of the setting,
and you must loop through,
or otherwise select from,
the elements of ARGLIST
to
process the specific settings you want
in whatever way is appropriate for your configuration.
For example,
the following code to let the user
add to the CPPDEFINES
construction variable
by specifying multiple
define=
settings on the command line:
cppdefines = [] for key, value in ARGLIST: if key == 'define': cppdefines.append(value) env = Environment(CPPDEFINES = cppdefines) env.Object('prog.c')
Yields the following output:
%scons -Q define=FOO
cc -o prog.o -c -DFOO prog.c %scons -Q define=FOO define=BAR
cc -o prog.o -c -DFOO -DBAR prog.c
Note that the ARGLIST
and ARGUMENTS
variables do not interfere with each other,
but merely provide slightly different views
into how the user specified
variable
=value
settings on the command line.
You can use both variables in the same
SCons configuration.
In general, the ARGUMENTS
dictionary
is more convenient to use,
(since you can just fetch variable
settings through a dictionary access),
and the ARGLIST
list
is more flexible
(since you can examine the
specific order in which
the user's command-line variabe settings).
Being able to use a command-line build variable like
debug=1
is handy,
but it can be a chore to write specific Python code
to recognize each such variable,
check for errors and provide appropriate messages,
and apply the values to a construction variable.
To help with this,
SCons supports a class to
define such build variables easily,
and a mechanism to apply the
build variables to a construction environment.
This allows you to control how the build variables affect
construction environments.
For example, suppose that you want users to set
a RELEASE
construction variable on the
command line whenever the time comes to build
a program for release,
and that the value of this variable
should be added to the command line
with the appropriate -D
option
(or other command line option)
to pass the value to the C compiler.
Here's how you might do that by setting
the appropriate value in a dictionary for the
$CPPDEFINES
construction variable:
vars = Variables(None, ARGUMENTS) vars.Add('RELEASE', 'Set to 1 to build for release', 0) env = Environment(variables = vars, CPPDEFINES={'RELEASE_BUILD' : '${RELEASE}'}) env.Program(['foo.c', 'bar.c'])
This SConstruct
file first creates a Variables
object
which uses the values from the command-line options dictionary ARGUMENTS
(the vars = Variables(None, ARGUMENTS)
call).
It then uses the object's Add
method to indicate that the RELEASE
variable can be set on the command line,
and that its default value will be 0
(the third argument to the Add
method).
The second argument is a line of help text;
we'll learn how to use it in the next section.
We then pass the created Variables
object as a variables
keyword argument
to the Environment
call
used to create the construction environment.
This then allows a user to set the
RELEASE
build variable on the command line
and have the variable show up in
the command line used to build each object from
a C source file:
% scons -Q RELEASE=1
cc -o bar.o -c -DRELEASE_BUILD=1 bar.c
cc -o foo.o -c -DRELEASE_BUILD=1 foo.c
cc -o foo foo.o bar.o
NOTE: Before SCons release 0.98.1, these build variables
were known as "command-line build options."
The class was actually named the Options
class,
and in the sections below,
the various functions were named
BoolOption
, EnumOption
, ListOption
,
PathOption
, PackageOption
and AddOptions
.
These older names still work,
and you may encounter them in older
SConscript
files,
but they have been officially deprecated
as of SCons version 2.0.
To make command-line build variables most useful,
you ideally want to provide
some help text that will describe
the available variables
when the user runs scons -h
.
You could write this text by hand,
but SCons provides an easier way.
Variables
objects support a
GenerateHelpText
method
that will, as its name suggests,
generate text that describes
the various variables that
have been added to it.
You then pass the output from this method to
the Help
function:
vars = Variables(None, ARGUMENTS) vars.Add('RELEASE', 'Set to 1 to build for release', 0) env = Environment(variables = vars) Help(vars.GenerateHelpText(env))
SCons will now display some useful text
when the -h
option is used:
% scons -Q -h
RELEASE: Set to 1 to build for release
default: 0
actual: 0
Use scons -H for help about command-line options.
Notice that the help output shows the default value, and the current actual value of the build variable.
Giving the user a way to specify the
value of a build variable on the command line
is useful,
but can still be tedious
if users must specify the variable
every time they run SCons.
We can let users provide customized build variable settings
in a local file by providing a
file name when we create the
Variables
object:
vars = Variables('custom.py') vars.Add('RELEASE', 'Set to 1 to build for release', 0) env = Environment(variables = vars, CPPDEFINES={'RELEASE_BUILD' : '${RELEASE}'}) env.Program(['foo.c', 'bar.c']) Help(vars.GenerateHelpText(env))
This then allows the user to control the RELEASE
variable by setting it in the custom.py
file:
RELEASE = 1
Note that this file is actually executed like a Python script. Now when we run SCons:
% scons -Q
cc -o bar.o -c -DRELEASE_BUILD=1 bar.c
cc -o foo.o -c -DRELEASE_BUILD=1 foo.c
cc -o foo foo.o bar.o
And if we change the contents of custom.py
to:
RELEASE = 0
The object files are rebuilt appropriately with the new variable:
% scons -Q
cc -o bar.o -c -DRELEASE_BUILD=0 bar.c
cc -o foo.o -c -DRELEASE_BUILD=0 foo.c
cc -o foo foo.o bar.o
Finally, you can combine both methods with:
vars = Variables('custom.py', ARGUMENTS)
where values in the option file custom.py
get overwritten
by the ones specified on the command line.
SCons provides a number of functions that provide ready-made behaviors for various types of command-line build variables.
It's often handy to be able to specify a
variable that controls a simple Boolean variable
with a true
or false
value.
It would be even more handy to accomodate
users who have different preferences for how to represent
true
or false
values.
The BoolVariable
function
makes it easy to accomodate these
common representations of
true
or false
.
The BoolVariable
function takes three arguments:
the name of the build variable,
the default value of the build variable,
and the help string for the variable.
It then returns appropriate information for
passing to the Add
method of a Variables
object, like so:
vars = Variables('custom.py') vars.Add(BoolVariable('RELEASE', 'Set to build for release', 0)) env = Environment(variables = vars, CPPDEFINES={'RELEASE_BUILD' : '${RELEASE}'}) env.Program('foo.c')
With this build variable,
the RELEASE
variable can now be enabled by
setting it to the value yes
or t
:
% scons -Q RELEASE=yes foo.o
cc -o foo.o -c -DRELEASE_BUILD=True foo.c
% scons -Q RELEASE=t foo.o
cc -o foo.o -c -DRELEASE_BUILD=True foo.c
Other values that equate to true
include
y
,
1
,
on
and
all
.
Conversely, RELEASE
may now be given a false
value by setting it to
no
or
f
:
% scons -Q RELEASE=no foo.o
cc -o foo.o -c -DRELEASE_BUILD=False foo.c
% scons -Q RELEASE=f foo.o
cc -o foo.o -c -DRELEASE_BUILD=False foo.c
Other values that equate to false
include
n
,
0
,
off
and
none
.
Lastly, if a user tries to specify any other value, SCons supplies an appropriate error message:
% scons -Q RELEASE=bad_value foo.o
scons: *** Error converting option: RELEASE
Invalid value for boolean option: bad_value
File "/home/my/project/SConstruct", line 4, in <module>
Suppose that we want a user to be able to
set a COLOR
variable
that selects a background color to be
displayed by an application,
but that we want to restrict the
choices to a specific set of allowed colors.
This can be set up quite easily
using the EnumVariable
,
which takes a list of allowed_values
in addition to the variable name,
default value,
and help text arguments:
vars = Variables('custom.py') vars.Add(EnumVariable('COLOR', 'Set background color', 'red', allowed_values=('red', 'green', 'blue'))) env = Environment(variables = vars, CPPDEFINES={'COLOR' : '"${COLOR}"'}) env.Program('foo.c')
The user can now explicity set the COLOR
build variable
to any of the specified allowed values:
%scons -Q COLOR=red foo.o
cc -o foo.o -c -DCOLOR="red" foo.c %scons -Q COLOR=blue foo.o
cc -o foo.o -c -DCOLOR="blue" foo.c %scons -Q COLOR=green foo.o
cc -o foo.o -c -DCOLOR="green" foo.c
But, almost more importantly,
an attempt to set COLOR
to a value that's not in the list
generates an error message:
% scons -Q COLOR=magenta foo.o
scons: *** Invalid value for option COLOR: magenta. Valid values are: ('red', 'green', 'blue')
File "/home/my/project/SConstruct", line 5, in <module>
The EnumVariable
function also supports a way
to map alternate names to allowed values.
Suppose, for example,
that we want to allow the user
to use the word navy
as a synonym for
blue
.
We do this by adding a map
dictionary
that will map its key values
to the desired legal value:
vars = Variables('custom.py') vars.Add(EnumVariable('COLOR', 'Set background color', 'red', allowed_values=('red', 'green', 'blue'), map={'navy':'blue'})) env = Environment(variables = vars, CPPDEFINES={'COLOR' : '"${COLOR}"'}) env.Program('foo.c')
As desired, the user can then use
navy
on the command line,
and SCons will translate it into blue
when it comes time to use the COLOR
variable to build a target:
% scons -Q COLOR=navy foo.o
cc -o foo.o -c -DCOLOR="blue" foo.c
By default, when using the EnumVariable
function,
arguments that differ
from the legal values
only in case
are treated as illegal values:
%scons -Q COLOR=Red foo.o
scons: *** Invalid value for option COLOR: Red. Valid values are: ('red', 'green', 'blue') File "/home/my/project/SConstruct", line 5, in <module> %scons -Q COLOR=BLUE foo.o
scons: *** Invalid value for option COLOR: BLUE. Valid values are: ('red', 'green', 'blue') File "/home/my/project/SConstruct", line 5, in <module> %scons -Q COLOR=nAvY foo.o
scons: *** Invalid value for option COLOR: nAvY. Valid values are: ('red', 'green', 'blue') File "/home/my/project/SConstruct", line 5, in <module>
The EnumVariable
function can take an additional
ignorecase
keyword argument that,
when set to 1
,
tells SCons to allow case differences
when the values are specified:
vars = Variables('custom.py') vars.Add(EnumVariable('COLOR', 'Set background color', 'red', allowed_values=('red', 'green', 'blue'), map={'navy':'blue'}, ignorecase=1)) env = Environment(variables = vars, CPPDEFINES={'COLOR' : '"${COLOR}"'}) env.Program('foo.c')
Which yields the output:
%scons -Q COLOR=Red foo.o
cc -o foo.o -c -DCOLOR="Red" foo.c %scons -Q COLOR=BLUE foo.o
cc -o foo.o -c -DCOLOR="BLUE" foo.c %scons -Q COLOR=nAvY foo.o
cc -o foo.o -c -DCOLOR="blue" foo.c %scons -Q COLOR=green foo.o
cc -o foo.o -c -DCOLOR="green" foo.c
Notice that an ignorecase
value of 1
preserves the case-spelling that the user supplied.
If you want SCons to translate the names
into lower-case,
regardless of the case used by the user,
specify an ignorecase
value of 2
:
vars = Variables('custom.py') vars.Add(EnumVariable('COLOR', 'Set background color', 'red', allowed_values=('red', 'green', 'blue'), map={'navy':'blue'}, ignorecase=2)) env = Environment(variables = vars, CPPDEFINES={'COLOR' : '"${COLOR}"'}) env.Program('foo.c')
Now SCons will use values of
red
,
green
or
blue
regardless of how the user spells
those values on the command line:
%scons -Q COLOR=Red foo.o
cc -o foo.o -c -DCOLOR="red" foo.c %scons -Q COLOR=nAvY foo.o
cc -o foo.o -c -DCOLOR="blue" foo.c %scons -Q COLOR=GREEN foo.o
cc -o foo.o -c -DCOLOR="green" foo.c
Another way in which you might want to allow users
to control a build variable is to
specify a list of one or more legal values.
SCons supports this through the ListVariable
function.
If, for example, we want a user to be able to set a
COLORS
variable to one or more of the legal list of values:
vars = Variables('custom.py') vars.Add(ListVariable('COLORS', 'List of colors', 0, ['red', 'green', 'blue'])) env = Environment(variables = vars, CPPDEFINES={'COLORS' : '"${COLORS}"'}) env.Program('foo.c')
A user can now specify a comma-separated list of legal values, which will get translated into a space-separated list for passing to the any build commands:
%scons -Q COLORS=red,blue foo.o
cc -o foo.o -c -DCOLORS="red blue" foo.c %scons -Q COLORS=blue,green,red foo.o
cc -o foo.o -c -DCOLORS="blue green red" foo.c
In addition, the ListVariable
function
allows the user to specify explicit keywords of
all
or none
to select all of the legal values,
or none of them, respectively:
%scons -Q COLORS=all foo.o
cc -o foo.o -c -DCOLORS="red green blue" foo.c %scons -Q COLORS=none foo.o
cc -o foo.o -c -DCOLORS="" foo.c
And, of course, an illegal value still generates an error message:
% scons -Q COLORS=magenta foo.o
scons: *** Error converting option: COLORS
Invalid value(s) for option: magenta
File "/home/my/project/SConstruct", line 5, in <module>
SCons supports a PathVariable
function
to make it easy to create a build variable
to control an expected path name.
If, for example, you need to
define a variable in the preprocessor
that controls the location of a
configuration file:
vars = Variables('custom.py') vars.Add(PathVariable('CONFIG', 'Path to configuration file', '/etc/my_config')) env = Environment(variables = vars, CPPDEFINES={'CONFIG_FILE' : '"$CONFIG"'}) env.Program('foo.c')
This then allows the user to
override the CONFIG
build variable
on the command line as necessary:
%scons -Q foo.o
cc -o foo.o -c -DCONFIG_FILE="/etc/my_config" foo.c %scons -Q CONFIG=/usr/local/etc/other_config foo.o
scons: `foo.o' is up to date.
By default, PathVariable
checks to make sure
that the specified path exists and generates an error if it
doesn't:
% scons -Q CONFIG=/does/not/exist foo.o
scons: *** Path for option CONFIG does not exist: /does/not/exist
File "/home/my/project/SConstruct", line 6, in <module>
PathVariable
provides a number of methods
that you can use to change this behavior.
If you want to ensure that any specified paths are,
in fact, files and not directories,
use the PathVariable.PathIsFile
method:
vars = Variables('custom.py') vars.Add(PathVariable('CONFIG', 'Path to configuration file', '/etc/my_config', PathVariable.PathIsFile)) env = Environment(variables = vars, CPPDEFINES={'CONFIG_FILE' : '"$CONFIG"'}) env.Program('foo.c')
Conversely, to ensure that any specified paths are
directories and not files,
use the PathVariable.PathIsDir
method:
vars = Variables('custom.py') vars.Add(PathVariable('DBDIR', 'Path to database directory', '/var/my_dbdir', PathVariable.PathIsDir)) env = Environment(variables = vars, CPPDEFINES={'DBDIR' : '"$DBDIR"'}) env.Program('foo.c')
If you want to make sure that any specified paths
are directories,
and you would like the directory created
if it doesn't already exist,
use the PathVariable.PathIsDirCreate
method:
vars = Variables('custom.py') vars.Add(PathVariable('DBDIR', 'Path to database directory', '/var/my_dbdir', PathVariable.PathIsDirCreate)) env = Environment(variables = vars, CPPDEFINES={'DBDIR' : '"$DBDIR"'}) env.Program('foo.c')
Lastly, if you don't care whether the path exists,
is a file, or a directory,
use the PathVariable.PathAccept
method
to accept any path that the user supplies:
vars = Variables('custom.py') vars.Add(PathVariable('OUTPUT', 'Path to output file or directory', None, PathVariable.PathAccept)) env = Environment(variables = vars, CPPDEFINES={'OUTPUT' : '"$OUTPUT"'}) env.Program('foo.c')
Sometimes you want to give users
even more control over a path name variable,
allowing them to explicitly enable or
disable the path name
by using yes
or no
keywords,
in addition to allow them
to supply an explicit path name.
SCons supports the PackageVariable
function to support this:
vars = Variables('custom.py') vars.Add(PackageVariable('PACKAGE', 'Location package', '/opt/location')) env = Environment(variables = vars, CPPDEFINES={'PACKAGE' : '"$PACKAGE"'}) env.Program('foo.c')
When the SConscript
file uses the PackageVariable
funciton,
user can now still use the default
or supply an overriding path name,
but can now explicitly set the
specified variable to a value
that indicates the package should be enabled
(in which case the default should be used)
or disabled:
%scons -Q foo.o
cc -o foo.o -c -DPACKAGE="/opt/location" foo.c %scons -Q PACKAGE=/usr/local/location foo.o
cc -o foo.o -c -DPACKAGE="/usr/local/location" foo.c %scons -Q PACKAGE=yes foo.o
cc -o foo.o -c -DPACKAGE="True" foo.c %scons -Q PACKAGE=no foo.o
cc -o foo.o -c -DPACKAGE="False" foo.c
Lastly, SCons provides a way to add
multiple build variables to a Variables
object at once.
Instead of having to call the Add
method
multiple times,
you can call the AddVariables
method with a list of build variables
to be added to the object.
Each build variable is specified
as either a tuple of arguments,
just like you'd pass to the Add
method itself,
or as a call to one of the pre-defined
functions for pre-packaged command-line build variables.
in any order:
vars = Variables() vars.AddVariables( ('RELEASE', 'Set to 1 to build for release', 0), ('CONFIG', 'Configuration file', '/etc/my_config'), BoolVariable('warnings', 'compilation with -Wall and similiar', 1), EnumVariable('debug', 'debug output and symbols', 'no', allowed_values=('yes', 'no', 'full'), map={}, ignorecase=0), # case sensitive ListVariable('shared', 'libraries to build as shared libraries', 'all', names = list_of_libs), PackageVariable('x11', 'use X11 installed here (yes = search some places)', 'yes'), PathVariable('qtdir', 'where the root of Qt is installed', qtdir), )
Users may, of course,
occasionally misspell variable names in their command-line settings.
SCons does not generate an error or warning
for any unknown variables the users specifies on the command line.
(This is in no small part because you may be
processing the arguments directly using the ARGUMENTS
dictionary,
and therefore SCons can't know in the general case
whether a given "misspelled" variable is
really unknown and a potential problem,
or something that your SConscript
file
will handle directly with some Python code.)
If, however, you're using a Variables
object to
define a specific set of command-line build variables
that you expect users to be able to set,
you may want to provide an error
message or warning of your own
if the user supplies a variable setting
that is not among
the defined list of variable names known to the Variables
object.
You can do this by calling the UnknownVariables
method of the Variables
object:
vars = Variables(None) vars.Add('RELEASE', 'Set to 1 to build for release', 0) env = Environment(variables = vars, CPPDEFINES={'RELEASE_BUILD' : '${RELEASE}'}) unknown = vars.UnknownVariables() if unknown: print("Unknown variables: %s"%unknown.keys()) Exit(1) env.Program('foo.c')
The UnknownVariables
method returns a dictionary
containing the keywords and values
of any variables the user specified on the command line
that are not
among the variables known to the Variables
object
(from having been specified using
the Variables
object'sAdd
method).
In the examble above,
we check for whether the dictionary
returned by the UnknownVariables
is non-empty,
and if so print the Python list
containing the names of the unknwown variables
and then call the Exit
function
to terminate SCons:
% scons -Q NOT_KNOWN=foo
Unknown variables: ['NOT_KNOWN']
Of course, you can process the items in the
dictionary returned by the UnknownVariables
function
in any way appropriate to your build configuration,
including just printing a warning message
but not exiting,
logging an error somewhere,
etc.
Note that you must delay the call of UnknownVariables
until after you have applied the Variables
object
to a construction environment
with the variables=
keyword argument of an Environment
call.
SCons supports a COMMAND_LINE_TARGETS
variable
that lets you fetch the list of targets that the
user specified on the command line.
You can use the targets to manipulate the
build in any way you wish.
As a simple example,
suppose that you want to print a reminder
to the user whenever a specific program is built.
You can do this by checking for the
target in the COMMAND_LINE_TARGETS
list:
if 'bar' in COMMAND_LINE_TARGETS: print("Don't forget to copy `bar' to the archive!") Default(Program('foo.c')) Program('bar.c')
Then, running SCons with the default target
works as it always does,
but explicity specifying the bar
target
on the command line generates the warning message:
%scons -Q
cc -o foo.o -c foo.c cc -o foo foo.o %scons -Q bar
Don't forget to copy `bar' to the archive! cc -o bar.o -c bar.c cc -o bar bar.o
Another practical use for the COMMAND_LINE_TARGETS
variable
might be to speed up a build
by only reading certain subsidiary SConscript
files if a specific target is requested.
One of the most basic things you can control
is which targets SCons will build by default--that is,
when there are no targets specified on the command line.
As mentioned previously,
SCons will normally build every target
in or below the current directory
by default--that is, when you don't
explicitly specify one or more targets
on the command line.
Sometimes, however, you may want
to specify explicitly that only
certain programs, or programs in certain directories,
should be built by default.
You do this with the Default
function:
env = Environment() hello = env.Program('hello.c') env.Program('goodbye.c') Default(hello)
This SConstruct
file knows how to build two programs,
hello
and goodbye
,
but only builds the
hello
program by default:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q
scons: `hello' is up to date. %scons -Q goodbye
cc -o goodbye.o -c goodbye.c cc -o goodbye goodbye.o
Note that, even when you use the Default
function in your SConstruct
file,
you can still explicitly specify the current directory
(.
) on the command line
to tell SCons to build
everything in (or below) the current directory:
% scons -Q .
cc -o goodbye.o -c goodbye.c
cc -o goodbye goodbye.o
cc -o hello.o -c hello.c
cc -o hello hello.o
You can also call the Default
function more than once,
in which case each call
adds to the list of targets to be built by default:
env = Environment() prog1 = env.Program('prog1.c') Default(prog1) prog2 = env.Program('prog2.c') prog3 = env.Program('prog3.c') Default(prog3)
Or you can specify more than one target
in a single call to the Default
function:
env = Environment() prog1 = env.Program('prog1.c') prog2 = env.Program('prog2.c') prog3 = env.Program('prog3.c') Default(prog1, prog3)
Either of these last two examples will build only the prog1 and prog3 programs by default:
%scons -Q
cc -o prog1.o -c prog1.c cc -o prog1 prog1.o cc -o prog3.o -c prog3.c cc -o prog3 prog3.o %scons -Q .
cc -o prog2.o -c prog2.c cc -o prog2 prog2.o
You can list a directory as
an argument to Default
:
env = Environment() env.Program(['prog1/main.c', 'prog1/foo.c']) env.Program(['prog2/main.c', 'prog2/bar.c']) Default('prog1')
In which case only the target(s) in that directory will be built by default:
%scons -Q
cc -o prog1/foo.o -c prog1/foo.c cc -o prog1/main.o -c prog1/main.c cc -o prog1/main prog1/main.o prog1/foo.o %scons -Q
scons: `prog1' is up to date. %scons -Q .
cc -o prog2/bar.o -c prog2/bar.c cc -o prog2/main.o -c prog2/main.c cc -o prog2/main prog2/main.o prog2/bar.o
Lastly, if for some reason you don't want
any targets built by default,
you can use the Python None
variable:
env = Environment() prog1 = env.Program('prog1.c') prog2 = env.Program('prog2.c') Default(None)
Which would produce build output like:
%scons -Q
scons: *** No targets specified and no Default() targets found. Stop. Found nothing to build %scons -Q .
cc -o prog1.o -c prog1.c cc -o prog1 prog1.o cc -o prog2.o -c prog2.c cc -o prog2 prog2.o
SCons supports a DEFAULT_TARGETS
variable
that lets you get at the current list of default targets.
The DEFAULT_TARGETS
variable has
two important differences from the COMMAND_LINE_TARGETS
variable.
First, the DEFAULT_TARGETS
variable is a list of
internal SCons nodes,
so you need to convert the list elements to strings
if you want to print them or look for a specific target name.
Fortunately, you can do this easily
by using the Python map
function
to run the list through str
:
prog1 = Program('prog1.c') Default(prog1) print("DEFAULT_TARGETS is %s"%map(str, DEFAULT_TARGETS))
(Keep in mind that all of the manipulation of the
DEFAULT_TARGETS
list takes place during the
first phase when SCons is reading up the SConscript
files,
which is obvious if
we leave off the -Q
flag when we run SCons:)
% scons
scons: Reading SConscript files ...
DEFAULT_TARGETS is ['prog1']
scons: done reading SConscript files.
scons: Building targets ...
cc -o prog1.o -c prog1.c
cc -o prog1 prog1.o
scons: done building targets.
Second,
the contents of the DEFAULT_TARGETS
list change
in response to calls to the Default
function,
as you can see from the following SConstruct
file:
prog1 = Program('prog1.c') Default(prog1) print("DEFAULT_TARGETS is now %s"%map(str, DEFAULT_TARGETS)) prog2 = Program('prog2.c') Default(prog2) print("DEFAULT_TARGETS is now %s"%map(str, DEFAULT_TARGETS))
Which yields the output:
% scons
scons: Reading SConscript files ...
DEFAULT_TARGETS is now ['prog1']
DEFAULT_TARGETS is now ['prog1', 'prog2']
scons: done reading SConscript files.
scons: Building targets ...
cc -o prog1.o -c prog1.c
cc -o prog1 prog1.o
cc -o prog2.o -c prog2.c
cc -o prog2 prog2.o
scons: done building targets.
In practice, this simply means that you
need to pay attention to the order in
which you call the Default
function
and refer to the DEFAULT_TARGETS
list,
to make sure that you don't examine the
list before you've added the default targets
you expect to find in it.
We've already been introduced to the
COMMAND_LINE_TARGETS
variable,
which contains a list of targets specified on the command line,
and the DEFAULT_TARGETS
variable,
which contains a list of targets specified
via calls to the Default
method or function.
Sometimes, however,
you want a list of whatever targets
SCons will try to build,
regardless of whether the targets came from the
command line or a Default
call.
You could code this up by hand, as follows:
if COMMAND_LINE_TARGETS: targets = COMMAND_LINE_TARGETS else: targets = DEFAULT_TARGETS
SCons, however, provides a convenient
BUILD_TARGETS
variable
that eliminates the need for this by-hand manipulation.
Essentially, the BUILD_TARGETS
variable
contains a list of the command-line targets,
if any were specified,
and if no command-line targets were specified,
it contains a list of the targets specified
via the Default
method or function.
Because BUILD_TARGETS
may contain a list of SCons nodes,
you must convert the list elements to strings
if you want to print them or look for a specific target name,
just like the DEFAULT_TARGETS
list:
prog1 = Program('prog1.c') Program('prog2.c') Default(prog1) print ("BUILD_TARGETS is %s"%map(str, BUILD_TARGETS))
Notice how the value of BUILD_TARGETS
changes depending on whether a target is
specified on the command line:
%scons -Q
BUILD_TARGETS is ['prog1'] cc -o prog1.o -c prog1.c cc -o prog1 prog1.o %scons -Q prog2
BUILD_TARGETS is ['prog2'] cc -o prog2.o -c prog2.c cc -o prog2 prog2.o %scons -Q -c .
BUILD_TARGETS is ['.'] Removed prog1.o Removed prog1 Removed prog2.o Removed prog2
Once a program is built,
it is often appropriate to install it in another
directory for public use.
You use the Install
method
to arrange for a program, or any other file,
to be copied into a destination directory:
env = Environment() hello = env.Program('hello.c') env.Install('/usr/bin', hello)
Note, however, that installing a file is
still considered a type of file "build."
This is important when you remember that
the default behavior of SCons is
to build files in or below the current directory.
If, as in the example above,
you are installing files in a directory
outside of the top-level SConstruct
file's directory tree,
you must specify that directory
(or a higher directory, such as /
)
for it to install anything there:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q /usr/bin
Install file: "hello" as "/usr/bin/hello"
It can, however, be cumbersome to remember
(and type) the specific destination directory
in which the program (or any other file)
should be installed.
This is an area where the Alias
function comes in handy,
allowing you, for example,
to create a pseudo-target named install
that can expand to the specified destination directory:
env = Environment() hello = env.Program('hello.c') env.Install('/usr/bin', hello) env.Alias('install', '/usr/bin')
This then yields the more natural ability to install the program in its destination as follows:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q install
Install file: "hello" as "/usr/bin/hello"
You can install multiple files into a directory
simply by calling the Install
function multiple times:
env = Environment() hello = env.Program('hello.c') goodbye = env.Program('goodbye.c') env.Install('/usr/bin', hello) env.Install('/usr/bin', goodbye) env.Alias('install', '/usr/bin')
Or, more succinctly, listing the multiple input files in a list (just like you can do with any other builder):
env = Environment() hello = env.Program('hello.c') goodbye = env.Program('goodbye.c') env.Install('/usr/bin', [hello, goodbye]) env.Alias('install', '/usr/bin')
Either of these two examples yields:
% scons -Q install
cc -o goodbye.o -c goodbye.c
cc -o goodbye goodbye.o
Install file: "goodbye" as "/usr/bin/goodbye"
cc -o hello.o -c hello.c
cc -o hello hello.o
Install file: "hello" as "/usr/bin/hello"
The Install
method preserves the name
of the file when it is copied into the
destination directory.
If you need to change the name of the file
when you copy it, use the InstallAs
function:
env = Environment() hello = env.Program('hello.c') env.InstallAs('/usr/bin/hello-new', hello) env.Alias('install', '/usr/bin')
This installs the hello
program with the name hello-new
as follows:
% scons -Q install
cc -o hello.o -c hello.c
cc -o hello hello.o
Install file: "hello" as "/usr/bin/hello-new"
Lastly, if you have multiple files that all
need to be installed with different file names,
you can either call the InstallAs
function
multiple times, or as a shorthand,
you can supply same-length lists
for both the target and source arguments:
env = Environment() hello = env.Program('hello.c') goodbye = env.Program('goodbye.c') env.InstallAs(['/usr/bin/hello-new', '/usr/bin/goodbye-new'], [hello, goodbye]) env.Alias('install', '/usr/bin')
In this case, the InstallAs
function
loops through both lists simultaneously,
and copies each source file into its corresponding
target file name:
% scons -Q install
cc -o goodbye.o -c goodbye.c
cc -o goodbye goodbye.o
Install file: "goodbye" as "/usr/bin/goodbye-new"
cc -o hello.o -c hello.c
cc -o hello hello.o
Install file: "hello" as "/usr/bin/hello-new"
SCons provides a number of platform-independent functions,
called factories
,
that perform common file system manipulations
like copying, moving or deleting files and directories,
or making directories.
These functions are factories
because they don't perform the action
at the time they're called,
they each return an Action
object
that can be executed at the appropriate time.
Suppose you want to arrange to make a copy of a file,
and don't have a suitable pre-existing builder.
[4]
One way would be to use the Copy
action factory
in conjunction with the Command
builder:
Command("file.out", "file.in", Copy("$TARGET", "$SOURCE"))
Notice that the action returned by the Copy
factory
will expand the $TARGET
and $SOURCE
strings
at the time file.out
is built,
and that the order of the arguments
is the same as that of a builder itself--that is,
target first, followed by source:
% scons -Q
Copy("file.out", "file.in")
You can, of course, name a file explicitly
instead of using $TARGET
or $SOURCE
:
Command("file.out", [], Copy("$TARGET", "file.in"))
Which executes as:
% scons -Q
Copy("file.out", "file.in")
The usefulness of the Copy
factory
becomes more apparent when
you use it in a list of actions
passed to the Command
builder.
For example, suppose you needed to run a
file through a utility that only modifies files in-place,
and can't "pipe" input to output.
One solution is to copy the source file
to a temporary file name,
run the utility,
and then copy the modified temporary file to the target,
which the Copy
factory makes extremely easy:
Command("file.out", "file.in", [ Copy("tempfile", "$SOURCE"), "modify tempfile", Copy("$TARGET", "tempfile"), ])
The output then looks like:
% scons -Q
Copy("tempfile", "file.in")
modify tempfile
Copy("file.out", "tempfile")
The Copy
factory has a third optional argument which controls
how symlinks are copied.
# Symbolic link shallow copied as a new symbolic link: Command("LinkIn", "LinkOut", Copy("$TARGET", "$SOURCE"[, True])) # Symbolic link target copied as a file or directory: Command("LinkIn", "FileOrDirectoryOut", Copy("$TARGET", "$SOURCE", False))
If you need to delete a file,
then the Delete
factory
can be used in much the same way as
the Copy
factory.
For example, if we want to make sure that
the temporary file
in our last example doesn't exist before
we copy to it,
we could add Delete
to the beginning
of the command list:
Command("file.out", "file.in", [ Delete("tempfile"), Copy("tempfile", "$SOURCE"), "modify tempfile", Copy("$TARGET", "tempfile"), ])
Which then executes as follows:
% scons -Q
Delete("tempfile")
Copy("tempfile", "file.in")
modify tempfile
Copy("file.out", "tempfile")
Of course, like all of these Action
factories,
the Delete
factory also expands
$TARGET
and $SOURCE
variables appropriately.
For example:
Command("file.out", "file.in", [ Delete("$TARGET"), Copy("$TARGET", "$SOURCE") ])
Executes as:
% scons -Q
Delete("file.out")
Copy("file.out", "file.in")
Note, however, that you typically don't need to
call the Delete
factory explicitly in this way;
by default, SCons deletes its target(s)
for you before executing any action.
One word of caution about using the Delete
factory:
it has the same variable expansions available
as any other factory, including the $SOURCE
variable.
Specifying Delete("$SOURCE")
is not something you usually want to do!
The Move
factory
allows you to rename a file or directory.
For example, if we don't want to copy the temporary file,
we could use:
Command("file.out", "file.in", [ Copy("tempfile", "$SOURCE"), "modify tempfile", Move("$TARGET", "tempfile"), ])
Which would execute as:
% scons -Q
Copy("tempfile", "file.in")
modify tempfile
Move("file.out", "tempfile")
If you just need to update the
recorded modification time for a file,
use the Touch
factory:
Command("file.out", "file.in", [ Copy("$TARGET", "$SOURCE"), Touch("$TARGET"), ])
Which executes as:
% scons -Q
Copy("file.out", "file.in")
Touch("file.out")
If you need to create a directory,
use the Mkdir
factory.
For example, if we need to process
a file in a temporary directory
in which the processing tool
will create other files that we don't care about,
you could use:
Command("file.out", "file.in", [ Delete("tempdir"), Mkdir("tempdir"), Copy("tempdir/${SOURCE.file}", "$SOURCE"), "process tempdir", Move("$TARGET", "tempdir/output_file"), Delete("tempdir"), ])
Which executes as:
% scons -Q
Delete("tempdir")
Mkdir("tempdir")
Copy("tempdir/file.in", "file.in")
process tempdir
Move("file.out", "tempdir/output_file")
scons: *** [file.out] tempdir/output_file: No such file or directory
To change permissions on a file or directory,
use the Chmod
factory.
The permission argument uses POSIX-style
permission bits and should typically
be expressed as an octal,
not decimal, number:
Command("file.out", "file.in", [ Copy("$TARGET", "$SOURCE"), Chmod("$TARGET", 0755), ])
Which executes:
% scons -Q
Copy("file.out", "file.in")
Chmod("file.out", 0755)
We've been showing you how to use Action
factories
in the Command
function.
You can also execute an Action
returned by a factory
(or actually, any Action
)
at the time the SConscript
file is read
by using the Execute
function.
For example, if we need to make sure that
a directory exists before we build any targets,
Execute(Mkdir('/tmp/my_temp_directory'))
Notice that this will
create the directory while
the SConscript
file is being read:
% scons
scons: Reading SConscript files ...
Mkdir("/tmp/my_temp_directory")
scons: done reading SConscript files.
scons: Building targets ...
scons: `.' is up to date.
scons: done building targets.
If you're familiar with Python,
you may wonder why you would want to use this
instead of just calling the native Python
os.mkdir()
function.
The advantage here is that the Mkdir
action will behave appropriately if the user
specifies the SCons -n
or
-q
options--that is,
it will print the action but not actually
make the directory when -n
is specified,
or make the directory but not print the action
when -q
is specified.
The Execute
function returns the exit status
or return value of the underlying action being executed.
It will also print an error message if the action
fails and returns a non-zero value.
SCons will not, however,
actually stop the build if the action fails.
If you want the build to stop
in response to a failure in an action called by Execute
,
you must do so by explicitly
checking the return value
and calling the Exit
function
(or a Python equivalent):
if Execute(Mkdir('/tmp/my_temp_directory')): # A problem occurred while making the temp directory. Exit(1)
[4]
Unfortunately, in the early days of SCons design,
we used the name Copy
for the function that
returns a copy of the environment,
otherwise that would be the logical choice for
a Builder that copies a file or directory tree
to a target location.
There are two occasions when SCons will,
by default, remove target files.
The first is when SCons determines that
an target file needs to be rebuilt
and removes the existing version of the target
before executing
The second is when SCons is invoked with the
-c
option to "clean"
a tree of its built targets.
These behaviours can be suppressed with the
Precious
and NoClean
functions, respectively.
By default, SCons removes targets before building them.
Sometimes, however, this is not what you want.
For example, you may want to update a library incrementally,
not by having it deleted and then rebuilt from all
of the constituent object files.
In such cases, you can use the
Precious
method to prevent
SCons from removing the target before it is built:
env = Environment(RANLIBCOM='') lib = env.Library('foo', ['f1.c', 'f2.c', 'f3.c']) env.Precious(lib)
Although the output doesn't look any different, SCons does not, in fact, delete the target library before rebuilding it:
% scons -Q
cc -o f1.o -c f1.c
cc -o f2.o -c f2.c
cc -o f3.o -c f3.c
ar rc libfoo.a f1.o f2.o f3.o
SCons will, however, still delete files marked as Precious
when the -c
option is used.
By default, SCons removes all built targets when invoked
with the -c
option to clean a source tree
of built targets.
Sometimes, however, this is not what you want.
For example, you may want to remove only intermediate generated files
(such as object files),
but leave the final targets
(the libraries)
untouched.
In such cases, you can use the NoClean
method to prevent SCons
from removing a target during a clean:
env = Environment(RANLIBCOM='') lib = env.Library('foo', ['f1.c', 'f2.c', 'f3.c']) env.NoClean(lib)
Notice that the libfoo.a
is not listed as a removed file:
%scons -Q
cc -o f1.o -c f1.c cc -o f2.o -c f2.c cc -o f3.o -c f3.c ar rc libfoo.a f1.o f2.o f3.o %scons -c
scons: Reading SConscript files ... scons: done reading SConscript files. scons: Cleaning targets ... Removed f1.o Removed f2.o Removed f3.o scons: done cleaning targets.
There may be additional files that you want removed
when the -c
option is used,
but which SCons doesn't know about
because they're not normal target files.
For example, perhaps a command you invoke
creates a log file as
part of building the target file you want.
You would like the log file cleaned,
but you don't want to have to teach
SCons that the command
"builds" two files.
You can use the Clean
function to arrange for additional files
to be removed when the -c
option is used.
Notice, however, that the Clean
function takes two arguments,
and the second argument
is the name of the additional file you want cleaned
(foo.log
in this example):
t = Command('foo.out', 'foo.in', 'build -o $TARGET $SOURCE') Clean(t, 'foo.log')
The first argument is the target with which you want
the cleaning of this additional file associated.
In the above example,
we've used the return value from the
Command
function,
which represents the
foo.out
target.
Now whenever the
foo.out
target is cleaned
by the -c
option,
the foo.log
file
will be removed as well:
%scons -Q
build -o foo.out foo.in %scons -Q -c
Removed foo.out Removed foo.log
The source code for large software projects
rarely stays in a single directory,
but is nearly always divided into a
hierarchy of directories.
Organizing a large software build using SCons
involves creating a hierarchy of build scripts
using the SConscript
function.
As we've already seen,
the build script at the top of the tree is called SConstruct
.
The top-level SConstruct
file can
use the SConscript
function to
include other subsidiary scripts in the build.
These subsidiary scripts can, in turn,
use the SConscript
function
to include still other scripts in the build.
By convention, these subsidiary scripts are usually
named SConscript
.
For example, a top-level SConstruct
file might
arrange for four subsidiary scripts to be included
in the build as follows:
SConscript(['drivers/display/SConscript', 'drivers/mouse/SConscript', 'parser/SConscript', 'utilities/SConscript'])
In this case, the SConstruct
file
lists all of the SConscript
files in the build explicitly.
(Note, however, that not every directory in the tree
necessarily has an SConscript
file.)
Alternatively, the drivers
subdirectory might contain an intermediate
SConscript
file,
in which case the SConscript
call in
the top-level SConstruct
file
would look like:
SConscript(['drivers/SConscript', 'parser/SConscript', 'utilities/SConscript'])
And the subsidiary SConscript
file in the
drivers
subdirectory
would look like:
SConscript(['display/SConscript', 'mouse/SConscript'])
Whether you list all of the SConscript
files in the
top-level SConstruct
file,
or place a subsidiary SConscript
file in
intervening directories,
or use some mix of the two schemes,
is up to you and the needs of your software.
Subsidiary SConscript
files make it easy to create a build
hierarchy because all of the file and directory names
in a subsidiary SConscript
files are interpreted
relative to the directory in which the SConscript
file lives.
Typically, this allows the SConscript
file containing the
instructions to build a target file
to live in the same directory as the source files
from which the target will be built,
making it easy to update how the software is built
whenever files are added or deleted
(or other changes are made).
For example, suppose we want to build two programs
prog1
and prog2
in two separate directories
with the same names as the programs.
One typical way to do this would be
with a top-level SConstruct
file like this:
SConscript(['prog1/SConscript', 'prog2/SConscript'])
And subsidiary SConscript
files that look like this:
env = Environment() env.Program('prog1', ['main.c', 'foo1.c', 'foo2.c'])
And this:
env = Environment() env.Program('prog2', ['main.c', 'bar1.c', 'bar2.c'])
Then, when we run SCons in the top-level directory, our build looks like:
% scons -Q
cc -o prog1/foo1.o -c prog1/foo1.c
cc -o prog1/foo2.o -c prog1/foo2.c
cc -o prog1/main.o -c prog1/main.c
cc -o prog1/prog1 prog1/main.o prog1/foo1.o prog1/foo2.o
cc -o prog2/bar1.o -c prog2/bar1.c
cc -o prog2/bar2.o -c prog2/bar2.c
cc -o prog2/main.o -c prog2/main.c
cc -o prog2/prog2 prog2/main.o prog2/bar1.o prog2/bar2.o
Notice the following:
First, you can have files with the same names
in multiple directories, like main.c in the above example.
Second, unlike standard recursive use of Make,
SCons stays in the top-level directory
(where the SConstruct
file lives)
and issues commands that use the path names
from the top-level directory to the
target and source files within the hierarchy.
If you need to use a file from another directory,
it's sometimes more convenient to specify
the path to a file in another directory
from the top-level SConstruct
directory,
even when you're using that file in
a subsidiary SConscript
file in a subdirectory.
You can tell SCons to interpret a path name
as relative to the top-level SConstruct
directory,
not the local directory of the SConscript
file,
by appending a #
(hash mark)
to the beginning of the path name:
env = Environment() env.Program('prog', ['main.c', '#lib/foo1.c', 'foo2.c'])
In this example,
the lib
directory is
directly underneath the top-level SConstruct
directory.
If the above SConscript
file is in a subdirectory
named src/prog
,
the output would look like:
% scons -Q
cc -o lib/foo1.o -c lib/foo1.c
cc -o src/prog/foo2.o -c src/prog/foo2.c
cc -o src/prog/main.o -c src/prog/main.c
cc -o src/prog/prog src/prog/main.o lib/foo1.o src/prog/foo2.o
(Notice that the lib/foo1.o
object file
is built in the same directory as its source file.
See Chapter 15, Separating Source and Build Directories, below,
for information about
how to build the object file in a different subdirectory.)
Of course, you can always specify an absolute path name for a file--for example:
env = Environment() env.Program('prog', ['main.c', '/usr/joe/lib/foo1.c', 'foo2.c'])
Which, when executed, would yield:
% scons -Q
cc -o src/prog/foo2.o -c src/prog/foo2.c
cc -o src/prog/main.o -c src/prog/main.c
cc -o /usr/joe/lib/foo1.o -c /usr/joe/lib/foo1.c
cc -o src/prog/prog src/prog/main.o /usr/joe/lib/foo1.o src/prog/foo2.o
(As was the case with top-relative path names,
notice that the /usr/joe/lib/foo1.o
object file
is built in the same directory as its source file.
See Chapter 15, Separating Source and Build Directories, below,
for information about
how to build the object file in a different subdirectory.)
In the previous example,
each of the subsidiary SConscript
files
created its own construction environment
by calling Environment
separately.
This obviously works fine,
but if each program must be built
with the same construction variables,
it's cumbersome and error-prone to initialize
separate construction environments
in the same way over and over in each subsidiary
SConscript
file.
SCons supports the ability to export variables
from a parent SConscript
file
to its subsidiary SConscript
files,
which allows you to share common initialized
values throughout your build hierarchy.
There are two ways to export a variable,
such as a construction environment,
from an SConscript
file,
so that it may be used by other SConscript
files.
First, you can call the Export
function with a list of variables,
or a string of white-space separated variable names.
Each call to Export
adds one
or more variables to a global list
of variables that are available for import
by other SConscript
files.
env = Environment() Export('env')
You may export more than one variable name at a time:
env = Environment() debug = ARGUMENTS['debug'] Export('env', 'debug')
Because white space is not legal in Python variable names,
the Export
function will even automatically split
a string into separate names for you:
Export('env debug')
Second, you can specify a list of
variables to export as a second argument
to the SConscript
function call:
SConscript('src/SConscript', 'env')
Or as the exports
keyword argument:
SConscript('src/SConscript', exports='env')
These calls export the specified variables
to only the listed SConscript
files.
You may, however, specify more than one
SConscript
file in a list:
SConscript(['src1/SConscript', 'src2/SConscript'], exports='env')
This is functionally equivalent to
calling the SConscript
function
multiple times with the same exports
argument,
one per SConscript
file.
Once a variable has been exported from a calling
SConscript
file,
it may be used in other SConscript
files
by calling the Import
function:
Import('env') env.Program('prog', ['prog.c'])
The Import
call makes the env
construction
environment available to the SConscript
file,
after which the variable can be used to build
programs, libraries, etc.
Like the Export
function,
the Import
function can be used
with multiple variable names:
Import('env', 'debug') env = env.Clone(DEBUG = debug) env.Program('prog', ['prog.c'])
And the Import
function will similarly
split a string along white-space
into separate variable names:
Import('env debug') env = env.Clone(DEBUG = debug) env.Program('prog', ['prog.c'])
Lastly, as a special case,
you may import all of the variables that
have been exported by supplying an asterisk
to the Import
function:
Import('*') env = env.Clone(DEBUG = debug) env.Program('prog', ['prog.c'])
If you're dealing with a lot of SConscript
files,
this can be a lot simpler than keeping
arbitrary lists of imported variables in each file.
Sometimes, you would like to be able to
use information from a subsidiary
SConscript
file in some way.
For example,
suppose that you want to create one
library from source files
scattered throughout a number
of subsidiary SConscript
files.
You can do this by using the Return
function to return values
from the subsidiary SConscript
files
to the calling file.
If, for example, we have two subdirectories
foo
and bar
that should each contribute a source
file to a Library,
what we'd like to be able to do is
collect the object files
from the subsidiary SConscript
calls
like this:
env = Environment() Export('env') objs = [] for subdir in ['foo', 'bar']: o = SConscript('%s/SConscript' % subdir) objs.append(o) env.Library('prog', objs)
We can do this by using the Return
function in the
foo/SConscript
file like this:
Import('env') obj = env.Object('foo.c') Return('obj')
(The corresponding
bar/SConscript
file should be pretty obvious.)
Then when we run SCons,
the object files from the subsidiary subdirectories
are all correctly archived in the desired library:
% scons -Q
cc -o bar/bar.o -c bar/bar.c
cc -o foo/foo.o -c foo/foo.c
ar rc libprog.a foo/foo.o bar/bar.o
ranlib libprog.a
It's often useful to keep any built files completely
separate from the source files.
In SCons, this is usually done by creating one or more separate
variant directory trees
that are used to hold the built objects files, libraries,
and executable programs, etc.
for a specific flavor, or variant, of build.
SCons provides two ways to do this,
one through the SConscript
function that we've already seen,
and the second through a more flexible VariantDir
function.
One historical note: the VariantDir
function
used to be called BuildDir
.
That name is still supported
but has been deprecated
because the SCons functionality
differs from the model of a "build directory"
implemented by other build systems like the GNU Autotools.
The most straightforward way to establish a variant directory tree
uses the fact that the usual way to
set up a build hierarchy is to have an
SConscript
file in the source subdirectory.
If you then pass a variant_dir
argument to the
SConscript
function call:
SConscript('src/SConscript', variant_dir='build')
SCons will then build all of the files in
the build
subdirectory:
%ls src
SConscript hello.c %scons -Q
cc -o build/hello.o -c build/hello.c cc -o build/hello build/hello.o %ls build
SConscript hello hello.c hello.o
But wait a minute--what's going on here?
SCons created the object file
build/hello.o
in the build
subdirectory,
as expected.
But even though our hello.c
file lives in the src
subdirectory,
SCons has actually compiled a
build/hello.c
file
to create the object file.
What's happened is that SCons has duplicated
the hello.c
file from the src
subdirectory
to the build
subdirectory,
and built the program from there.
The next section explains why SCons does this.
SCons duplicates source files in variant directory trees because it's the most straightforward way to guarantee a correct build regardless of include-file directory paths, relative references between files, or tool support for putting files in different locations, and the SCons philosophy is to, by default, guarantee a correct build in all cases.
The most direct reason to duplicate source files in variant directories is simply that some tools (mostly older versions) are written to only build their output files in the same directory as the source files. In this case, the choices are either to build the output file in the source directory and move it to the variant directory, or to duplicate the source files in the variant directory.
Additionally,
relative references between files
can cause problems if we don't
just duplicate the hierarchy of source files
in the variant directory.
You can see this at work in
use of the C preprocessor #include
mechanism with double quotes, not angle brackets:
#include "file.h"
The de facto standard behavior
for most C compilers in this case
is to first look in the same directory
as the source file that contains the #include
line,
then to look in the directories in the preprocessor search path.
Add to this that the SCons implementation of
support for code repositories
(described below)
means not all of the files
will be found in the same directory hierarchy,
and the simplest way to make sure
that the right include file is found
is to duplicate the source files into the variant directory,
which provides a correct build
regardless of the original location(s) of the source files.
Although source-file duplication guarantees a correct build even in these end-cases, it can usually be safely disabled. The next section describes how you can disable the duplication of source files in the variant directory.
In most cases and with most tool sets,
SCons can place its target files in a build subdirectory
without
duplicating the source files
and everything will work just fine.
You can disable the default SCons behavior
by specifying duplicate=0
when you call the SConscript
function:
SConscript('src/SConscript', variant_dir='build', duplicate=0)
When this flag is specified, SCons uses the variant directory like most people expect--that is, the output files are placed in the variant directory while the source files stay in the source directory:
%ls src
SConscript hello.c %scons -Q
cc -c src/hello.c -o build/hello.o cc -o build/hello build/hello.o %ls build
hello hello.o
Use the VariantDir
function to establish that target
files should be built in a separate directory
from the source files:
VariantDir('build', 'src') env = Environment() env.Program('build/hello.c')
Note that when you're not using
an SConscript
file in the src
subdirectory,
you must actually specify that
the program must be built from
the build/hello.c
file that SCons will duplicate in the
build
subdirectory.
When using the VariantDir
function directly,
SCons still duplicates the source files
in the variant directory by default:
%ls src
hello.c %scons -Q
cc -o build/hello.o -c build/hello.c cc -o build/hello build/hello.o %ls build
hello hello.c hello.o
You can specify the same duplicate=0
argument
that you can specify for an SConscript
call:
VariantDir('build', 'src', duplicate=0) env = Environment() env.Program('build/hello.c')
In which case SCons will disable duplication of the source files:
%ls src
hello.c %scons -Q
cc -o build/hello.o -c src/hello.c cc -o build/hello build/hello.o %ls build
hello hello.o
Even when using the VariantDir
function,
it's much more natural to use it with
a subsidiary SConscript
file.
For example, if the
src/SConscript
looks like this:
env = Environment() env.Program('hello.c')
Then our SConstruct
file could look like:
VariantDir('build', 'src') SConscript('build/SConscript')
Yielding the following output:
%ls src
SConscript hello.c %scons -Q
cc -o build/hello.o -c build/hello.c cc -o build/hello build/hello.o %ls build
SConscript hello hello.c hello.o
Notice that this is completely equivalent
to the use of SConscript
that we
learned about in the previous section.
The Glob
file name pattern matching function
works just as usual when using VariantDir
.
For example, if the
src/SConscript
looks like this:
env = Environment() env.Program('hello', Glob('*.c'))
Then with the same SConstruct
file as in the previous section,
and source files f1.c
and f2.c
in src,
we would see the following output:
%ls src
SConscript f1.c f2.c f2.h %scons -Q
cc -o build/f1.o -c build/f1.c cc -o build/f2.o -c build/f2.c cc -o build/hello build/f1.o build/f2.o %ls build
SConscript f1.c f1.o f2.c f2.h f2.o hello
The Glob
function returns Nodes in the
build/
tree, as you'd expect.
The variant_dir
keyword argument of
the SConscript
function provides everything
we need to show how easy it is to create
variant builds using SCons.
Suppose, for example, that we want to
build a program for both Windows and Linux platforms,
but that we want to build it in a shared directory
with separate side-by-side build directories
for the Windows and Linux versions of the program.
platform = ARGUMENTS.get('OS', Platform()) include = "#export/$PLATFORM/include" lib = "#export/$PLATFORM/lib" bin = "#export/$PLATFORM/bin" env = Environment(PLATFORM = platform, BINDIR = bin, INCDIR = include, LIBDIR = lib, CPPPATH = [include], LIBPATH = [lib], LIBS = 'world') Export('env') env.SConscript('src/SConscript', variant_dir='build/$PLATFORM')
This SConstruct file, when run on a Linux system, yields:
% scons -Q OS=linux
Install file: "build/linux/world/world.h" as "export/linux/include/world.h"
cc -o build/linux/hello/hello.o -c -Iexport/linux/include build/linux/hello/hello.c
cc -o build/linux/world/world.o -c -Iexport/linux/include build/linux/world/world.c
ar rc build/linux/world/libworld.a build/linux/world/world.o
ranlib build/linux/world/libworld.a
Install file: "build/linux/world/libworld.a" as "export/linux/lib/libworld.a"
cc -o build/linux/hello/hello build/linux/hello/hello.o -Lexport/linux/lib -lworld
Install file: "build/linux/hello/hello" as "export/linux/bin/hello"
The same SConstruct file on Windows would build:
C:\>scons -Q OS=windows
Install file: "build/windows/world/world.h" as "export/windows/include/world.h"
cl /Fobuild\windows\hello\hello.obj /c build\windows\hello\hello.c /nologo /Iexport\windows\include
cl /Fobuild\windows\world\world.obj /c build\windows\world\world.c /nologo /Iexport\windows\include
lib /nologo /OUT:build\windows\world\world.lib build\windows\world\world.obj
Install file: "build/windows/world/world.lib" as "export/windows/lib/world.lib"
link /nologo /OUT:build\windows\hello\hello.exe /LIBPATH:export\windows\lib world.lib build\windows\hello\hello.obj
embedManifestExeCheck(target, source, env)
Install file: "build/windows/hello/hello.exe" as "export/windows/bin/hello.exe"
The gettext
toolset supports internationalization and localization
of SCons-based projects. Builders provided by gettext
automatize
generation and updates of translation files. You can manage translations and
translation templates similarly to how it's done with autotools.
To follow examples provided in this chapter set up your operating system to
support two or more languages. In following examples we use locales
en_US
, de_DE
, and
pl_PL
.
Ensure, that you have GNU gettext utilities installed on your system.
To edit translation files you may wish to install poedit editor.
Let's start with a very simple project, the "Hello world" program for example
/* hello.c */ #include <stdio.h> int main(int argc, char* argv[]) { printf("Hello world\n"); return 0; }
Prepare a SConstruct
to compile the program
as usual.
# SConstruct env = Environment() hello = Program(["hello.c"])
Now we'll convert the project to a multi-lingual one. If you don't
already have GNU gettext
utilities installed, install them from your preffered
package repository, or download from
http://ftp.gnu.org/gnu/gettext/. For the purpose of this example,
you should have following three locales installed on your system:
en_US
, de_DE
and
pl_PL
. On debian, for example, you may enable certain
locales through dpkg-reconfigure locales.
First prepare the hello.c
program for
internationalization. Change the previous code so it reads as follows:
/* hello.c */ #include <stdio.h> #include <libintl.h> #include <locale.h> int main(int argc, char* argv[]) { bindtextdomain("hello", "locale"); setlocale(LC_ALL, ""); textdomain("hello"); printf(gettext("Hello world\n")); return 0; }
Detailed recipes for such conversion can
be found at
http://www.gnu.org/software/gettext/manual/gettext.html#Sources.
The gettext("...")
has two purposes.
First, it marks messages for the xgettext(1) program, which
we will use to extract from the sources the messages for localization.
Second, it calls the gettext
library internals to
translate the message at runtime.
Now we shall instruct SCons how to generate and maintain translation files.
For that, use the Translate
builder and MOFiles
builder.
The first one takes source files, extracts internationalized
messages from them, creates so-called POT
file
(translation template), and then creates PO
translation
files, one for each requested language. Later, during the development
lifecycle, the builder keeps all these files up-to date. The
MOFiles
builder compiles the PO
files to binary
form. Then install the MO
files under directory
called locale
.
The completed
SConstruct
is as follows:
# SConstruct env = Environment( tools = ['default', 'gettext'] ) hello = env.Program(["hello.c"]) env['XGETTEXTFLAGS'] = [ '--package-name=%s' % 'hello', '--package-version=%s' % '1.0', ] po = env.Translate(["pl","en", "de"], ["hello.c"], POAUTOINIT = 1) mo = env.MOFiles(po) InstallAs(["locale/en/LC_MESSAGES/hello.mo"], ["en.mo"]) InstallAs(["locale/pl/LC_MESSAGES/hello.mo"], ["pl.mo"]) InstallAs(["locale/de/LC_MESSAGES/hello.mo"], ["de.mo"])
Generate the translation files with scons po-update. You should see the output from SCons simillar to this:
user@host:$ scons po-update scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... Entering '/home/ptomulik/projects/tmp' xgettext --package-name=hello --package-version=1.0 -o - hello.c Leaving '/home/ptomulik/projects/tmp' Writting 'messages.pot' (new file) msginit --no-translator -l pl -i messages.pot -o pl.po Created pl.po. msginit --no-translator -l en -i messages.pot -o en.po Created en.po. msginit --no-translator -l de -i messages.pot -o de.po Created de.po. scons: done building targets.
If everything is right, you should see following new files.
user@host:$ ls *.po* de.po en.po messages.pot pl.po
Open en.po
in poedit and provide
the English translation to message "Hello world\n"
. Do the
same for de.po
(deutsch) and
pl.po
(polish). Let the translations be, for example:
en: "Welcome to beautiful world!\n"
de: "Hallo Welt!\n"
pl: "Witaj swiecie!\n"
Now compile the project by executing scons. The output should be similar to this:
user@host:$ scons scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... msgfmt -c -o de.mo de.po msgfmt -c -o en.mo en.po gcc -o hello.o -c hello.c gcc -o hello hello.o Install file: "de.mo" as "locale/de/LC_MESSAGES/hello.mo" Install file: "en.mo" as "locale/en/LC_MESSAGES/hello.mo" msgfmt -c -o pl.mo pl.po Install file: "pl.mo" as "locale/pl/LC_MESSAGES/hello.mo" scons: done building targets.
SCons automatically compiled the PO
files to binary format
MO
, and the InstallAs
lines installed
these files under locale
folder.
Your program should be now ready. You may try it as follows (linux):
user@host:$ LANG=en_US.UTF-8 ./hello Welcome to beautiful world
user@host:$ LANG=de_DE.UTF-8 ./hello Hallo Welt
user@host:$ LANG=pl_PL.UTF-8 ./hello Witaj swiecie
To demonstrate the further life of translation files, let's change Polish
translation (poedit pl.po) to "Witaj drogi
swiecie\n"
. Run scons to see how scons
reacts to this
user@host:$scons scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... msgfmt -c -o pl.mo pl.po Install file: "pl.mo" as "locale/pl/LC_MESSAGES/hello.mo" scons: done building targets.
Now, open hello.c
and add another one
printf
line with new message.
/* hello.c */ #include <stdio.h> #include <libintl.h> #include <locale.h> int main(int argc, char* argv[]) { bindtextdomain("hello", "locale"); setlocale(LC_ALL, ""); textdomain("hello"); printf(gettext("Hello world\n")); printf(gettext("and good bye\n")); return 0; }
Compile project with scons. This time, the
msgmerge(1) program is used by SCons to update
PO
file. The output from compilation is like:
user@host:$scons scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... Entering '/home/ptomulik/projects/tmp' xgettext --package-name=hello --package-version=1.0 -o - hello.c Leaving '/home/ptomulik/projects/tmp' Writting 'messages.pot' (messages in file were outdated) msgmerge --update de.po messages.pot ... done. msgfmt -c -o de.mo de.po msgmerge --update en.po messages.pot ... done. msgfmt -c -o en.mo en.po gcc -o hello.o -c hello.c gcc -o hello hello.o Install file: "de.mo" as "locale/de/LC_MESSAGES/hello.mo" Install file: "en.mo" as "locale/en/LC_MESSAGES/hello.mo" msgmerge --update pl.po messages.pot ... done. msgfmt -c -o pl.mo pl.po Install file: "pl.mo" as "locale/pl/LC_MESSAGES/hello.mo" scons: done building targets.
The next example demonstrates what happens if we change the source code
in such way that the internationalized messages do not change. The answer
is that none of translation files (POT
,
PO
) are touched (i.e. no content changes, no
creation/modification time changed and so on). Let's append another
line to the program (after the last printf), so its code becomes:
/* hello.c */ #include <stdio.h> #include <libintl.h> #include <locale.h> int main(int argc, char* argv[]) { bindtextdomain("hello", "locale"); setlocale(LC_ALL, ""); textdomain("hello"); printf(gettext("Hello world\n")); printf(gettext("and good bye\n")); printf("----------------\n"); return a; }
Compile the project. You'll see on your screen
user@host:$scons scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... Entering '/home/ptomulik/projects/tmp' xgettext --package-name=hello --package-version=1.0 -o - hello.c Leaving '/home/ptomulik/projects/tmp' Not writting 'messages.pot' (messages in file found to be up-to-date) gcc -o hello.o -c hello.c gcc -o hello hello.o scons: done building targets.
As you see, the internationalized messages ditn't change, so the
POT
and the rest of translation files have not
even been touched.
Although SCons provides many useful methods
for building common software products
(programs, libraries, documents, etc.),
you frequently want to be
able to build some other type of file
not supported directly by SCons.
Fortunately, SCons makes it very easy
to define your own Builder
objects
for any custom file types you want to build.
(In fact, the SCons interfaces for creating
Builder
objects are flexible enough and easy enough to use
that all of the the SCons built-in Builder
objects
are created using the mechanisms described in this section.)
The simplest Builder
to create is
one that executes an external command.
For example, if we want to build
an output file by running the contents
of the input file through a command named
foobuild
,
creating that Builder
might look like:
bld = Builder(action = 'foobuild < $SOURCE > $TARGET')
All the above line does is create a free-standing
Builder
object.
The next section will show us how to actually use it.
A Builder
object isn't useful
until it's attached to a construction environment
so that we can call it to arrange
for files to be built.
This is done through the $BUILDERS
construction variable
in an environment.
The $BUILDERS
variable is a Python dictionary
that maps the names by which you want to call
various Builder
objects to the objects themselves.
For example, if we want to call the
Builder
we just defined by the name
Foo
,
our SConstruct
file might look like:
bld = Builder(action = 'foobuild < $SOURCE > $TARGET') env = Environment(BUILDERS = {'Foo' : bld})
With the Builder
attached to our construction environment
with the name Foo
,
we can now actually call it like so:
env.Foo('file.foo', 'file.input')
Then when we run SCons it looks like:
% scons -Q
foobuild < file.input > file.foo
Note, however, that the default $BUILDERS
variable in a construction environment
comes with a default set of Builder
objects
already defined:
Program
, Library
, etc.
And when we explicitly set the $BUILDERS
variable
when we create the construction environment
,
the default Builder
s are no longer part of
the environment:
bld = Builder(action = 'foobuild < $SOURCE > $TARGET') env = Environment(BUILDERS = {'Foo' : bld}) env.Foo('file.foo', 'file.input') env.Program('hello.c')
% scons -Q
AttributeError: 'SConsEnvironment' object has no attribute 'Program':
File "/home/my/project/SConstruct", line 4:
env.Program('hello.c')
To be able to use both our own defined Builder
objects
and the default Builder
objects in the same construction environment
,
you can either add to the $BUILDERS
variable
using the Append
function:
env = Environment() bld = Builder(action = 'foobuild < $SOURCE > $TARGET') env.Append(BUILDERS = {'Foo' : bld}) env.Foo('file.foo', 'file.input') env.Program('hello.c')
Or you can explicitly set the appropriately-named
key in the $BUILDERS
dictionary:
env = Environment() bld = Builder(action = 'foobuild < $SOURCE > $TARGET') env['BUILDERS']['Foo'] = bld env.Foo('file.foo', 'file.input') env.Program('hello.c')
Either way, the same construction environment
can then use both the newly-defined
Foo
Builder
and the default Program
Builder
:
% scons -Q
foobuild < file.input > file.foo
cc -o hello.o -c hello.c
cc -o hello hello.o
By supplying additional information
when you create a Builder
,
you can let SCons add appropriate file
suffixes to the target and/or the source file.
For example, rather than having to specify
explicitly that you want the Foo
Builder
to build the file.foo
target file from the file.input
source file,
you can give the .foo
and .input
suffixes to the Builder
,
making for more compact and readable calls to
the Foo
Builder
:
bld = Builder(action = 'foobuild < $SOURCE > $TARGET', suffix = '.foo', src_suffix = '.input') env = Environment(BUILDERS = {'Foo' : bld}) env.Foo('file1') env.Foo('file2')
% scons -Q
foobuild < file1.input > file1.foo
foobuild < file2.input > file2.foo
You can also supply a prefix
keyword argument
if it's appropriate to have SCons append a prefix
to the beginning of target file names.
In SCons, you don't have to call an external command
to build a file.
You can, instead, define a Python function
that a Builder
object can invoke
to build your target file (or files).
Such a builder function
definition looks like:
def build_function(target, source, env): # Code to build "target" from "source" return None
The arguments of a builder function
are:
A list of Node objects representing
the target or targets to be
built by this builder function.
The file names of these target(s)
may be extracted using the Python str
function.
A list of Node objects representing
the sources to be
used by this builder function to build the targets.
The file names of these source(s)
may be extracted using the Python str
function.
The construction environment
used for building the target(s).
The builder function may use any of the
environment's construction variables
in any way to affect how it builds the targets.
The builder function must
return a 0
or None
value
if the target(s) are built successfully.
The builder function
may raise an exception
or return any non-zero value
to indicate that the build is unsuccessful.
Once you've defined the Python function
that will build your target file,
defining a Builder
object for it is as
simple as specifying the name of the function,
instead of an external command,
as the Builder
's
action
argument:
def build_function(target, source, env): # Code to build "target" from "source" return None bld = Builder(action = build_function, suffix = '.foo', src_suffix = '.input') env = Environment(BUILDERS = {'Foo' : bld}) env.Foo('file')
And notice that the output changes slightly, reflecting the fact that a Python function, not an external command, is now called to build the target file:
% scons -Q
build_function(["file.foo"], ["file.input"])
SCons Builder objects can create an action "on the fly"
by using a function called a generator
.
This provides a great deal of flexibility to
construct just the right list of commands
to build your target.
A generator
looks like:
def generate_actions(source, target, env, for_signature): return 'foobuild < %s > %s' % (target[0], source[0])
The arguments of a generator
are:
A list of Node objects representing
the sources to be built
by the command or other action
generated by this function.
The file names of these source(s)
may be extracted using the Python str
function.
A list of Node objects representing
the target or targets to be built
by the command or other action
generated by this function.
The file names of these target(s)
may be extracted using the Python str
function.
The construction environment
used for building the target(s).
The generator may use any of the
environment's construction variables
in any way to determine what command
or other action to return.
A flag that specifies whether the generator is being called to contribute to a build signature, as opposed to actually executing the command.
The generator
must return a
command string or other action that will be used to
build the specified target(s) from the specified source(s).
Once you've defined a generator
,
you create a Builder
to use it
by specifying the generator keyword argument
instead of action
.
def generate_actions(source, target, env, for_signature): return 'foobuild < %s > %s' % (source[0], target[0]) bld = Builder(generator = generate_actions, suffix = '.foo', src_suffix = '.input') env = Environment(BUILDERS = {'Foo' : bld}) env.Foo('file')
% scons -Q
foobuild < file.input > file.foo
Note that it's illegal to specify both an
action
and a
generator
for a Builder
.
SCons supports the ability for a Builder to modify the
lists of target(s) from the specified source(s).
You do this by defining an emitter
function
that takes as its arguments
the list of the targets passed to the builder,
the list of the sources passed to the builder,
and the construction environment.
The emitter function should return the modified
lists of targets that should be built
and sources from which the targets will be built.
For example, suppose you want to define a Builder
that always calls a foobuild
program,
and you want to automatically add
a new target file named
new_target
and a new source file named
new_source
whenever it's called.
The SConstruct
file might look like this:
def modify_targets(target, source, env): target.append('new_target') source.append('new_source') return target, source bld = Builder(action = 'foobuild $TARGETS - $SOURCES', suffix = '.foo', src_suffix = '.input', emitter = modify_targets) env = Environment(BUILDERS = {'Foo' : bld}) env.Foo('file')
And would yield the following output:
% scons -Q
foobuild file.foo new_target - file.input new_source
One very flexible thing that you can do is
use a construction variable to specify
different emitter functions for different
construction variable.
To do this, specify a string
containing a construction variable
expansion as the emitter when you call
the Builder
function,
and set that construction variable to
the desired emitter function
in different construction environments:
bld = Builder(action = 'my_command $SOURCES > $TARGET', suffix = '.foo', src_suffix = '.input', emitter = '$MY_EMITTER') def modify1(target, source, env): return target, source + ['modify1.in'] def modify2(target, source, env): return target, source + ['modify2.in'] env1 = Environment(BUILDERS = {'Foo' : bld}, MY_EMITTER = modify1) env2 = Environment(BUILDERS = {'Foo' : bld}, MY_EMITTER = modify2) env1.Foo('file1') env2.Foo('file2') import os env1['ENV']['PATH'] = env2['ENV']['PATH'] + os.pathsep + os.getcwd() env2['ENV']['PATH'] = env2['ENV']['PATH'] + os.pathsep + os.getcwd()
bld = Builder(action = 'my_command $SOURCES > $TARGET', suffix = '.foo', src_suffix = '.input', emitter = '$MY_EMITTER') def modify1(target, source, env): return target, source + ['modify1.in'] def modify2(target, source, env): return target, source + ['modify2.in'] env1 = Environment(BUILDERS = {'Foo' : bld}, MY_EMITTER = modify1) env2 = Environment(BUILDERS = {'Foo' : bld}, MY_EMITTER = modify2) env1.Foo('file1') env2.Foo('file2')
In this example, the modify1.in
and modify2.in
files
get added to the source lists
of the different commands:
% scons -Q
my_command file1.input modify1.in > file1.foo
my_command file2.input modify2.in > file2.foo
The site_scons
directories give you a place to
put Python modules and packages that you can import into your SConscript
files
(site_scons
),
add-on tools that can integrate into SCons
(site_scons/site_tools
),
and a site_scons/site_init.py
file that
gets read before any SConstruct
or SConscript
file,
allowing you to change SCons's default behavior.
Each system type (Windows, Mac, Linux, etc.) searches a canonical set of directories for site_scons; see the man page for details. The top-level SConstruct's site_scons dir is always searched last, and its dir is placed first in the tool path so it overrides all others.
If you get a tool from somewhere (the SCons wiki or a third party,
for instance) and you'd like to use it in your project, a
site_scons
dir is the simplest place to put it.
Tools come in two flavors; either a Python function that operates on
an Environment
or a Python module or package containing two functions,
exists()
and generate()
.
A single-function Tool can just be included in your
site_scons/site_init.py
file where it will be
parsed and made available for use. For instance, you could have a
site_scons/site_init.py
file like this:
def TOOL_ADD_HEADER(env): """A Tool to add a header from $HEADER to the source file""" add_header = Builder(action=['echo "$HEADER" > $TARGET', 'cat $SOURCE >> $TARGET']) env.Append(BUILDERS = {'AddHeader' : add_header}) env['HEADER'] = '' # set default value
and a SConstruct
like this:
# Use TOOL_ADD_HEADER from site_scons/site_init.py env=Environment(tools=['default', TOOL_ADD_HEADER], HEADER="=====") env.AddHeader('tgt', 'src')
The TOOL_ADD_HEADER
tool method will be
called to add the AddHeader
tool to the
environment.
A more full-fledged tool with
exists()
and generate()
methods can be installed either as a module in the file
site_scons/site_tools/toolname.py
or as a
package in the
directory site_scons/site_tools/toolname
. In
the case of using a package, the exists()
and generate()
are in the
file site_scons/site_tools/toolname/__init__.py
.
(In all the above case toolname
is replaced
by the name of the tool.)
Since site_scons/site_tools
is automatically
added to the head of the tool search path, any tool found there
will be available to all environments. Furthermore, a tool found
there will override a built-in tool of the same name, so if you
need to change the behavior of a built-in
tool, site_scons
gives you the hook you need.
Many people have a library of utility Python functions they'd like
to include in SConscript
s; just put that module in
site_scons/my_utils.py
or any valid Python module name of your
choice. For instance you can do something like this in
site_scons/my_utils.py
to add
build_id
and MakeWorkDir
functions:
from SCons.Script import * # for Execute and Mkdir def build_id(): """Return a build ID (stub version)""" return "100" def MakeWorkDir(workdir): """Create the specified dir immediately""" Execute(Mkdir(workdir))
And then in your SConscript
or any sub-SConscript
anywhere in
your build, you can import my_utils
and use it:
import my_utils print("build_id=" + my_utils.build_id()) my_utils.MakeWorkDir('/tmp/work')
Note that although you can put this library in
site_scons/site_init.py
,
it is no better there than site_scons/my_utils.py
since you still have to import that module into your SConscript
.
Also note that in order to refer to objects in the SCons namespace
such as Environment
or Mkdir
or Execute
in any file other
than a SConstruct
or SConscript
you always need to do
from SCons.Script import *
This is true in modules in site_scons
such as
site_scons/site_init.py
as well.
You can use any of the user- or machine-wide site dirs such as
~/.scons/site_scons
instead of
./site_scons
, or use the
--site-dir
option to point to your own dir.
site_init.py
and
site_tools
will be located under that dir.
To avoid using a site_scons
dir at all,
even if it exists, use the --no-site-dir
option.
Creating a Builder
and attaching it to a construction environment
allows for a lot of flexibility when you
want to re-use actions
to build multiple files of the same type.
This can, however, be cumbersome
if you only need to execute one specific command
to build a single file (or group of files).
For these situations, SCons supports a
Command
Builder
that arranges
for a specific action to be executed
to build a specific file or files.
This looks a lot like the other builders
(like Program
, Object
, etc.),
but takes as an additional argument
the command to be executed to build the file:
env = Environment() env.Command('foo.out', 'foo.in', "sed 's/x/y/' < $SOURCE > $TARGET")
When executed,
SCons runs the specified command,
substituting $SOURCE
and $TARGET
as expected:
% scons -Q
sed 's/x/y/' < foo.in > foo.out
This is often more convenient than
creating a Builder
object
and adding it to the $BUILDERS
variable
of a construction environment
Note that the action you specify to the
Command
Builder
can be any legal SCons Action
,
such as a Python function:
env = Environment() def build(target, source, env): # Whatever it takes to build return None env.Command('foo.out', 'foo.in', build)
Which executes as follows:
% scons -Q
build(["foo.out"], ["foo.in"])
Note that $SOURCE
and $TARGET
are expanded
in the source and target as well as of SCons 1.1,
so you can write:
env.Command('${SOURCE.basename}.out', 'foo.in', build)
which does the same thing as the previous example, but allows you to avoid repeating yourself.
The AddMethod
function is used to add a method
to an environment. It's typically used to add a "pseudo-builder,"
a function that looks like a Builder
but
wraps up calls to multiple other Builder
s
or otherwise processes its arguments
before calling one or more Builder
s.
In the following example,
we want to install the program into the standard
/usr/bin
directory hierarchy,
but also copy it into a local install/bin
directory from which a package might be built:
def install_in_bin_dirs(env, source): """Install source in both bin dirs""" i1 = env.Install("$BIN", source) i2 = env.Install("$LOCALBIN", source) return [i1[0], i2[0]] # Return a list, like a normal builder env = Environment(BIN='/usr/bin', LOCALBIN='#install/bin') env.AddMethod(install_in_bin_dirs, "InstallInBinDirs") env.InstallInBinDirs(Program('hello.c')) # installs hello in both bin dirs
This produces the following:
% scons -Q /
cc -o hello.o -c hello.c
cc -o hello hello.o
Install file: "hello" as "/usr/bin/hello"
Install file: "hello" as "install/bin/hello"
As mentioned, a pseudo-builder also provides more flexibility
in parsing arguments than you can get with a Builder
.
The next example shows a pseudo-builder with a
named argument that modifies the filename, and a separate argument
for the resource file (rather than having the builder figure it out
by file extension). This example also demonstrates using the global
AddMethod
function to add a method to the global Environment class,
so it will be used in all subsequently created environments.
def BuildTestProg(env, testfile, resourcefile, testdir="tests"): """Build the test program; prepends "test_" to src and target, and puts target into testdir.""" srcfile = "test_%s.c" % testfile target = "%s/test_%s" % (testdir, testfile) if env['PLATFORM'] == 'win32': resfile = env.RES(resourcefile) p = env.Program(target, [srcfile, resfile]) else: p = env.Program(target, srcfile) return p AddMethod(Environment, BuildTestProg) env = Environment() env.BuildTestProg('stuff', resourcefile='res.rc')
This produces the following on Linux:
% scons -Q
cc -o test_stuff.o -c test_stuff.c
cc -o tests/test_stuff test_stuff.o
And the following on Windows:
C:\>scons -Q
rc /fores.res res.rc
cl /Fotest_stuff.obj /c test_stuff.c /nologo
link /nologo /OUT:tests\test_stuff.exe test_stuff.obj res.res
embedManifestExeCheck(target, source, env)
Using AddMethod
is better than just adding an instance method
to a construction environment
because it gets called as a proper method,
and because AddMethod
provides for copying the method
to any clones of the construction environment
instance.
SCons has built-in scanners that know how to look in
C, Fortran and IDL source files for information about
other files that targets built from those files depend on--for example,
in the case of files that use the C preprocessor,
the .h
files that are specified
using #include
lines in the source.
You can use the same mechanisms that SCons uses to create
its built-in scanners to write scanners of your own for file types
that SCons does not know how to scan "out of the box."
Suppose, for example, that we want to create a simple scanner
for .foo
files.
A .foo
file contains some text that
will be processed,
and can include other files on lines that begin
with include
followed by a file name:
include filename.foo
Scanning a file will be handled by a Python function
that you must supply.
Here is a function that will use the Python
re
module
to scan for the include
lines in our example:
import re include_re = re.compile(r'^include\s+(\S+)$', re.M) def kfile_scan(node, env, path, arg): contents = node.get_text_contents() return env.File(include_re.findall(contents))
It is important to note that you
have to return a list of File nodes from the scanner function, simple
strings for the file names won't do. As in the examples we are showing here,
you can use the File
function of your current Environment in order to create nodes on the fly from
a sequence of file names with relative paths.
The scanner function must accept the four specified arguments and return a list of implicit dependencies. Presumably, these would be dependencies found from examining the contents of the file, although the function can perform any manipulation at all to generate the list of dependencies.
An SCons node object representing the file being scanned.
The path name to the file can be
used by converting the node to a string
using the str()
function,
or an internal SCons get_text_contents()
object method can be used to fetch the contents.
The construction environment in effect for this scan. The scanner function may choose to use construction variables from this environment to affect its behavior.
A list of directories that form the search path for included files
for this scanner.
This is how SCons handles the $CPPPATH
and $LIBPATH
variables.
An optional argument that you can choose to have passed to this scanner function by various scanner instances.
A Scanner object is created using the Scanner
function,
which typically takes an skeys
argument
to associate the type of file suffix with this scanner.
The Scanner object must then be associated with the
$SCANNERS
construction variable of a construction environment,
typically by using the Append
method:
kscan = Scanner(function = kfile_scan, skeys = ['.k']) env.Append(SCANNERS = kscan)
When we put it all together, it looks like:
import re include_re = re.compile(r'^include\s+(\S+)$', re.M) def kfile_scan(node, env, path): contents = node.get_text_contents() includes = include_re.findall(contents) return env.File(includes) kscan = Scanner(function = kfile_scan, skeys = ['.k']) env = Environment(ENV = {'PATH' : '/usr/local/bin'}) env.Append(SCANNERS = kscan) env.Command('foo', 'foo.k', 'kprocess < $SOURCES > $TARGET')
Many scanners need to search for included files or dependencies
using a path variable; this is how $CPPPATH
and
$LIBPATH
work. The path to search is passed to your
scanner as the path
argument. Path variables
may be lists of nodes, semicolon-separated strings, or even
contain SCons variables which need to be expanded. Fortunately,
SCons provides the FindPathDirs
function which itself returns
a function to expand a given path (given as a SCons construction
variable name) to a list of paths at the time the scanner is
called. Deferring evaluation until that point allows, for
instance, the path to contain $TARGET references which differ for
each file scanned.
Using FindPathDirs
is quite easy. Continuing the above example,
using KPATH as the construction variable with the search path
(analogous to $CPPPATH
), we just modify the Scanner
constructor call to include a path keyword arg:
kscan = Scanner(function = kfile_scan, skeys = ['.k'], path_function = FindPathDirs('KPATH'))
FindPathDirs returns a callable object that, when called, will essentially expand the elements in env['KPATH'] and tell the scanner to search in those dirs. It will also properly add related repository and variant dirs to the search list. As a side note, the returned method stores the path in an efficient way so lookups are fast even when variable substitutions may be needed. This is important since many files get scanned in a typical build.
One approach for the use of scanners is with builders.
There are two optional parameters we can use with a builder
source_scanner
and target_scanner
.
def kfile_scan(node, env, path, arg): contents = node.get_text_contents() return env.File(include_re.findall(contents)) kscan = Scanner(function = kfile_scan, skeys = ['.k'], path_function = FindPathDirs('KPATH')) def build_function(target, source, env): # Code to build "target" from "source" return None bld = Builder(action = build_function, suffix = '.foo', source_scanner = kscan src_suffix = '.input') env = Environment(BUILDERS = {'Foo' : bld}) env.Foo('file')
An emitter function can modify the list of sources or targets passed to the action function when the builder is triggered.
A scanner function will not affect the list of sources or targets seen by the builder during the build action. The scanner function will however affect if the builder should be rebuilt (if any of the files sourced by the scanner have changed for example).
Often, a software project will have one or more central repositories, directory trees that contain source code, or derived files, or both. You can eliminate additional unnecessary rebuilds of files by having SCons use files from one or more code repositories to build files in your local build tree.
It's often useful to allow multiple programmers working
on a project to build software from
source files and/or derived files that
are stored in a centrally-accessible repository,
a directory copy of the source code tree.
(Note that this is not the sort of repository
maintained by a source code management system
like BitKeeper, CVS, or Subversion.)
You use the Repository
method
to tell SCons to search one or more
central code repositories (in order)
for any source files and derived files
that are not present in the local build tree:
env = Environment() env.Program('hello.c') Repository('/usr/repository1', '/usr/repository2')
Multiple calls to the Repository
method
will simply add repositories to the global list
that SCons maintains,
with the exception that SCons will automatically eliminate
the current directory and any non-existent
directories from the list.
The above example
specifies that SCons
will first search for files under
the /usr/repository1
tree
and next under the /usr/repository2
tree.
SCons expects that any files it searches
for will be found in the same position
relative to the top-level directory.
In the above example, if the hello.c
file is not
found in the local build tree,
SCons will search first for
a /usr/repository1/hello.c
file
and then for a /usr/repository2/hello.c
file
to use in its place.
So given the SConstruct
file above,
if the hello.c
file exists in the local
build directory,
SCons will rebuild the hello
program
as normal:
% scons -Q
cc -o hello.o -c hello.c
cc -o hello hello.o
If, however, there is no local hello.c
file,
but one exists in /usr/repository1
,
SCons will recompile the hello
program
from the source file it finds in the repository:
% scons -Q
cc -o hello.o -c /usr/repository1/hello.c
cc -o hello hello.o
And similarly, if there is no local hello.c
file
and no /usr/repository1/hello.c
,
but one exists in /usr/repository2
:
% scons -Q
cc -o hello.o -c /usr/repository2/hello.c
cc -o hello hello.o
We've already seen that SCons will scan the contents of
a source file for #include
file names
and realize that targets built from that source file
also depend on the #include
file(s).
For each directory in the $CPPPATH
list,
SCons will actually search the corresponding directories
in any repository trees and establish the
correct dependencies on any
#include
files that it finds
in repository directory.
Unless the C compiler also knows about these directories
in the repository trees, though,
it will be unable to find the #include
files.
If, for example, the hello.c
file in
our previous example includes the hello.h
in its current directory,
and the hello.h
only exists in the repository:
% scons -Q
cc -o hello.o -c hello.c
hello.c:1: hello.h: No such file or directory
In order to inform the C compiler about the repositories,
SCons will add appropriate
-I
flags to the compilation commands
for each directory in the $CPPPATH
list.
So if we add the current directory to the
construction environment $CPPPATH
like so:
env = Environment(CPPPATH = ['.']) env.Program('hello.c') Repository('/usr/repository1')
Then re-executing SCons yields:
% scons -Q
cc -o hello.o -c -I. -I/usr/repository1 hello.c
cc -o hello hello.o
The order of the -I
options replicates,
for the C preprocessor,
the same repository-directory search path
that SCons uses for its own dependency analysis.
If there are multiple repositories and multiple $CPPPATH
directories, SCons will add the repository directories
to the beginning of each $CPPPATH
directory,
rapidly multiplying the number of -I
flags.
If, for example, the $CPPPATH
contains three directories
(and shorter repository path names!):
env = Environment(CPPPATH = ['dir1', 'dir2', 'dir3']) env.Program('hello.c') Repository('/r1', '/r2')
Then we'll end up with nine -I
options
on the command line,
three (for each of the $CPPPATH
directories)
times three (for the local directory plus the two repositories):
% scons -Q
cc -o hello.o -c -Idir1 -I/r1/dir1 -I/r2/dir1 -Idir2 -I/r1/dir2 -I/r2/dir2 -Idir3 -I/r1/dir3 -I/r2/dir3 hello.c
cc -o hello hello.o
SCons relies on the C compiler's
-I
options to control the order in which
the preprocessor will search the repository directories
for #include
files.
This causes a problem, however, with how the C preprocessor
handles #include
lines with
the file name included in double-quotes.
As we've seen,
SCons will compile the hello.c
file from
the repository if it doesn't exist in
the local directory.
If, however, the hello.c
file in the repository contains
a #include
line with the file name in
double quotes:
#include "hello.h" int main(int argc, char *argv[]) { printf(HELLO_MESSAGE); return (0); }
Then the C preprocessor will always
use a hello.h
file from the repository directory first,
even if there is a hello.h
file in the local directory,
despite the fact that the command line specifies
-I
as the first option:
% scons -Q
cc -o hello.o -c -I. -I/usr/repository1 /usr/repository1/hello.c
cc -o hello hello.o
This behavior of the C preprocessor--always search
for a #include
file in double-quotes
first in the same directory as the source file,
and only then search the -I
--can
not, in general, be changed.
In other words, it's a limitation
that must be lived with if you want to use
code repositories in this way.
There are three ways you can possibly
work around this C preprocessor behavior:
Some modern versions of C compilers do have an option
to disable or control this behavior.
If so, add that option to $CFLAGS
(or $CXXFLAGS
or both) in your construction environment(s).
Make sure the option is used for all construction
environments that use C preprocessing!
Change all occurrences of #include "file.h"
to #include <file.h>
.
Use of #include
with angle brackets
does not have the same behavior--the -I
directories are searched first
for #include
files--which
gives SCons direct control over the list of
directories the C preprocessor will search.
Require that everyone working with compilation from repositories check out and work on entire directories of files, not individual files. (If you use local wrapper scripts around your source code control system's command, you could add logic to enforce this restriction there.
SCons will also search in repositories
for the SConstruct
file and any specified SConscript
files.
This poses a problem, though: how can SCons search a
repository tree for an SConstruct
file
if the SConstruct
file itself contains the information
about the pathname of the repository?
To solve this problem, SCons allows you
to specify repository directories
on the command line using the -Y
option:
% scons -Q -Y /usr/repository1 -Y /usr/repository2
When looking for source or derived files,
SCons will first search the repositories
specified on the command line,
and then search the repositories
specified in the SConstruct
or SConscript
files.
If a repository contains not only source files,
but also derived files (such as object files,
libraries, or executables), SCons will perform
its normal MD5 signature calculation to
decide if a derived file in a repository is up-to-date,
or the derived file must be rebuilt in the local build directory.
For the SCons signature calculation to work correctly,
a repository tree must contain the .sconsign
files
that SCons uses to keep track of signature information.
Usually, this would be done by a build integrator
who would run SCons in the repository
to create all of its derived files and .sconsign
files,
or who would run SCons in a separate build directory
and copy the resulting tree to the desired repository:
%cd /usr/repository1
%scons -Q
cc -o file1.o -c file1.c cc -o file2.o -c file2.c cc -o hello.o -c hello.c cc -o hello hello.o file1.o file2.o
(Note that this is safe even if the SConstruct
file
lists /usr/repository1
as a repository,
because SCons will remove the current build directory
from its repository list for that invocation.)
Now, with the repository populated,
we only need to create the one local source file
we're interested in working with at the moment,
and use the -Y
option to
tell SCons to fetch any other files it needs
from the repository:
%cd $HOME/build
%edit hello.c
%scons -Q -Y /usr/repository1
cc -c -o hello.o hello.c cc -o hello hello.o /usr/repository1/file1.o /usr/repository1/file2.o
Notice that SCons realizes that it does not need to
rebuild local copies file1.o
and file2.o
files,
but instead uses the already-compiled files
from the repository.
If the repository tree contains the complete results of a build, and we try to build from the repository without any files in our local tree, something moderately surprising happens:
%mkdir $HOME/build2
%cd $HOME/build2
%scons -Q -Y /usr/all/repository hello
scons: `hello' is up-to-date.
Why does SCons say that the hello
program
is up-to-date when there is no hello
program
in the local build directory?
Because the repository (not the local directory)
contains the up-to-date hello
program,
and SCons correctly determines that nothing
needs to be done to rebuild that
up-to-date copy of the file.
There are, however, many times when you want to ensure that a
local copy of a file always exists.
A packaging or testing script, for example,
may assume that certain generated files exist locally.
To tell SCons to make a copy of any up-to-date repository
file in the local build directory,
use the Local
function:
env = Environment() hello = env.Program('hello.c') Local(hello)
If we then run the same command, SCons will make a local copy of the program from the repository copy, and tell you that it is doing so:
% scons -Y /usr/all/repository hello
Local copy of hello from /usr/all/repository/hello
scons: `hello' is up-to-date.
(Notice that, because the act of making the local copy
is not considered a "build" of the hello
file,
SCons still reports that it is up-to-date.)
SCons has integrated support for multi-platform build configuration similar to that offered by GNU Autoconf, such as figuring out what libraries or header files are available on the local system. This section describes how to use this SCons feature.
This chapter is still under development, so not everything is explained as well as it should be. See the SCons man page for additional information.
The basic framework for multi-platform build configuration
in SCons is to attach a configure context
to a
construction environment by calling the Configure
function,
perform a number of checks for
libraries, functions, header files, etc.,
and to then call the configure context's Finish
method
to finish off the configuration:
env = Environment() conf = Configure(env) # Checks for libraries, header files, etc. go here! env = conf.Finish()
SCons provides a number of basic checks, as well as a mechanism for adding your own custom checks.
Note that SCons uses its own dependency mechanism to determine when a check needs to be run--that is, SCons does not run the checks every time it is invoked, but caches the values returned by previous checks and uses the cached values unless something has changed. This saves a tremendous amount of developer time while working on cross-platform build issues.
The next sections describe the basic checks that SCons supports, as well as how to add your own custom checks.
Testing the existence of a header file
requires knowing what language the header file is.
A configure context has a CheckCHeader
method
that checks for the existence of a C header file:
env = Environment() conf = Configure(env) if not conf.CheckCHeader('math.h'): print 'Math.h must be installed!' Exit(1) if conf.CheckCHeader('foo.h'): conf.env.Append('-DHAS_FOO_H') env = conf.Finish()
Note that you can choose to terminate the build if a given header file doesn't exist, or you can modify the construction environment based on the existence of a header file.
If you need to check for the existence
a C++ header file,
use the CheckCXXHeader
method:
env = Environment() conf = Configure(env) if not conf.CheckCXXHeader('vector.h'): print 'vector.h must be installed!' Exit(1) env = conf.Finish()
Check for the availability of a specific function
using the CheckFunc
method:
env = Environment() conf = Configure(env) if not conf.CheckFunc('strcpy'): print 'Did not find strcpy(), using local version' conf.env.Append(CPPDEFINES = '-Dstrcpy=my_local_strcpy') env = conf.Finish()
Check for the availability of a library
using the CheckLib
method.
You only specify the basename of the library,
you don't need to add a lib
prefix or a .a
or .lib
suffix:
env = Environment() conf = Configure(env) if not conf.CheckLib('m'): print 'Did not find libm.a or m.lib, exiting!' Exit(1) env = conf.Finish()
Because the ability to use a library successfully
often depends on having access to a header file
that describes the library's interface,
you can check for a library
and a header file
at the same time by using the
CheckLibWithHeader
method:
env = Environment() conf = Configure(env) if not conf.CheckLibWithHeader('m', 'math.h', 'c'): print 'Did not find libm.a or m.lib, exiting!' Exit(1) env = conf.Finish()
This is essentially shorthand for
separate calls to the CheckHeader
and CheckLib
functions.
Check for the availability of a typedef
by using the CheckType
method:
env = Environment() conf = Configure(env) if not conf.CheckType('off_t'): print 'Did not find off_t typedef, assuming int' conf.env.Append(CCFLAGS = '-Doff_t=int') env = conf.Finish()
You can also add a string that will be
placed at the beginning of the test file
that will be used to check for the typedef
.
This provide a way to specify
files that must be included to find the typedef
:
env = Environment() conf = Configure(env) if not conf.CheckType('off_t', '#include <sys/types.h>\n'): print 'Did not find off_t typedef, assuming int' conf.env.Append(CCFLAGS = '-Doff_t=int') env = conf.Finish()
Check the size of a datatype by using the CheckTypeSize
method:
env = Environment() conf = Configure(env) int_size = conf.CheckTypeSize('unsigned int') print 'sizeof unsigned int is', int_size env = conf.Finish()
% scons -Q
sizeof unsigned int is 4
scons: `.' is up to date.
Check for the presence of a program
by using the CheckProg
method:
env = Environment() conf = Configure(env) if not conf.CheckProg('foobar'): print 'Unable to find the program foobar on the system' Exit(1) env = conf.Finish()
A custom check is a Python function that checks for a certain condition to exist on the running system, usually using methods that SCons supplies to take care of the details of checking whether a compilation succeeds, a link succeeds, a program is runnable, etc. A simple custom check for the existence of a specific library might look as follows:
mylib_test_source_file = """ #include <mylib.h> int main(int argc, char **argv) { MyLibrary mylib(argc, argv); return 0; } """ def CheckMyLibrary(context): context.Message('Checking for MyLibrary...') result = context.TryLink(mylib_test_source_file, '.c') context.Result(result) return result
The Message
and Result
methods
should typically begin and end a custom check to
let the user know what's going on:
the Message
call prints the
specified message (with no trailing newline)
and the Result
call prints
yes
if the check succeeds and
no
if it doesn't.
The TryLink
method
actually tests for whether the
specified program text
will successfully link.
(Note that a custom check can modify
its check based on any arguments you
choose to pass it,
or by using or modifying the configure context environment
in the context.env
attribute.)
This custom check function is
then attached to the configure context
by passing a dictionary
to the Configure
call
that maps a name of the check
to the underlying function:
env = Environment() conf = Configure(env, custom_tests = {'CheckMyLibrary' : CheckMyLibrary})
You'll typically want to make the check and the function name the same, as we've done here, to avoid potential confusion.
We can then put these pieces together
and actually call the CheckMyLibrary
check
as follows:
mylib_test_source_file = """ #include <mylib.h> int main(int argc, char **argv) { MyLibrary mylib(argc, argv); return 0; } """ def CheckMyLibrary(context): context.Message('Checking for MyLibrary... ') result = context.TryLink(mylib_test_source_file, '.c') context.Result(result) return result env = Environment() conf = Configure(env, custom_tests = {'CheckMyLibrary' : CheckMyLibrary}) if not conf.CheckMyLibrary(): print 'MyLibrary is not installed!' Exit(1) env = conf.Finish() # We would then add actual calls like Program() to build # something using the "env" construction environment.
If MyLibrary is not installed on the system, the output will look like:
% scons
scons: Reading SConscript file ...
Checking for MyLibrary... no
MyLibrary is not installed!
If MyLibrary is installed, the output will look like:
% scons
scons: Reading SConscript file ...
Checking for MyLibrary... yes
scons: done reading SConscript
scons: Building targets ...
.
.
.
Using multi-platform configuration
as described in the previous sections
will run the configuration commands
even when invoking
scons -c
to clean targets:
% scons -Q -c
Checking for MyLibrary... yes
Removed foo.o
Removed foo
Although running the platform checks
when removing targets doesn't hurt anything,
it's usually unnecessary.
You can avoid this by using the
GetOption
method to
check whether the -c
(clean)
option has been invoked on the command line:
env = Environment() if not env.GetOption('clean'): conf = Configure(env, custom_tests = {'CheckMyLibrary' : CheckMyLibrary}) if not conf.CheckMyLibrary(): print 'MyLibrary is not installed!' Exit(1) env = conf.Finish()
% scons -Q -c
Removed foo.o
Removed foo
On multi-developer software projects, you can sometimes speed up every developer's builds a lot by allowing them to share the derived files that they build. SCons makes this easy, as well as reliable.
To enable sharing of derived files,
use the CacheDir
function
in any SConscript
file:
CacheDir('/usr/local/build_cache')
Note that the directory you specify must already exist and be readable and writable by all developers who will be sharing derived files. It should also be in some central location that all builds will be able to access. In environments where developers are using separate systems (like individual workstations) for builds, this directory would typically be on a shared or NFS-mounted file system.
Here's what happens:
When a build has a CacheDir
specified,
every time a file is built,
it is stored in the shared cache directory
along with its MD5 build signature.
[5]
On subsequent builds,
before an action is invoked to build a file,
SCons will check the shared cache directory
to see if a file with the exact same build
signature already exists.
If so, the derived file will not be built locally,
but will be copied into the local build directory
from the shared cache directory,
like so:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q -c
Removed hello.o Removed hello %scons -Q
Retrieved `hello.o' from cache Retrieved `hello' from cache
Note that the CacheDir
feature still calculates
MD5 build sigantures for the shared cache file names
even if you configure SCons to use timestamps
to decide if files are up to date.
(See the Chapter 6, Dependencies
chapter for information about the Decider
function.)
Consequently, using CacheDir
may reduce or eliminate any
potential performance improvements
from using timestamps for up-to-date decisions.
One potential drawback to using a shared cache is that the output printed by SCons can be inconsistent from invocation to invocation, because any given file may be rebuilt one time and retrieved from the shared cache the next time. This can make analyzing build output more difficult, especially for automated scripts that expect consistent output each time.
If, however, you use the --cache-show
option,
SCons will print the command line that it
would have executed
to build the file,
even when it is retrieving the file from the shared cache.
This makes the build output consistent
every time the build is run:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q -c
Removed hello.o Removed hello %scons -Q --cache-show
cc -o hello.o -c hello.c cc -o hello hello.o
The trade-off, of course, is that you no longer know whether or not SCons has retrieved a derived file from cache or has rebuilt it locally.
You may want to disable caching for certain
specific files in your configuration.
For example, if you only want to put
executable files in a central cache,
but not the intermediate object files,
you can use the NoCache
function to specify that the
object files should not be cached:
env = Environment() obj = env.Object('hello.c') env.Program('hello.c') CacheDir('cache') NoCache('hello.o')
Then when you run scons
after cleaning
the built targets,
it will recompile the object file locally
(since it doesn't exist in the shared cache directory),
but still realize that the shared cache directory
contains an up-to-date executable program
that can be retrieved instead of re-linking:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q -c
Removed hello.o Removed hello %scons -Q
cc -o hello.o -c hello.c Retrieved `hello' from cache
Retrieving an already-built file from the shared cache is usually a significant time-savings over rebuilding the file, but how much of a savings (or even whether it saves time at all) can depend a great deal on your system or network configuration. For example, retrieving cached files from a busy server over a busy network might end up being slower than rebuilding the files locally.
In these cases, you can specify
the --cache-disable
command-line option to tell SCons
to not retrieve already-built files from the
shared cache directory:
%scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q -c
Removed hello.o Removed hello %scons -Q
Retrieved `hello.o' from cache Retrieved `hello' from cache %scons -Q -c
Removed hello.o Removed hello %scons -Q --cache-disable
cc -o hello.o -c hello.c cc -o hello hello.o
Sometimes, you may have one or more derived files already built in your local build tree that you wish to make available to other people doing builds. For example, you may find it more effective to perform integration builds with the cache disabled (per the previous section) and only populate the shared cache directory with the built files after the integration build has completed successfully. This way, the cache will only get filled up with derived files that are part of a complete, successful build not with files that might be later overwritten while you debug integration problems.
In this case, you can use the
the --cache-force
option
to tell SCons to put all derived files in the cache,
even if the files already exist in your local tree
from having been built by a previous invocation:
%scons -Q --cache-disable
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q -c
Removed hello.o Removed hello %scons -Q --cache-disable
cc -o hello.o -c hello.c cc -o hello hello.o %scons -Q --cache-force
scons: `.' is up to date. %scons -Q
scons: `.' is up to date.
Notice how the above sample run
demonstrates that the --cache-disable
option avoids putting the built
hello.o
and
hello
files in the cache,
but after using the --cache-force
option,
the files have been put in the cache
for the next invocation to retrieve.
If you allow multiple builds to update the shared cache directory simultaneously, two builds that occur at the same time can sometimes start "racing" with one another to build the same files in the same order. If, for example, you are linking multiple files into an executable program:
Program('prog', ['f1.c', 'f2.c', 'f3.c', 'f4.c', 'f5.c'])
SCons will normally build the input object files on which the program depends in their normal, sorted order:
% scons -Q
cc -o f5.o -c f5.c
cc -o f4.o -c f4.c
cc -o f1.o -c f1.c
cc -o f3.o -c f3.c
cc -o f2.o -c f2.c
cc -o prog f1.o f2.o f3.o f4.o f5.o
But if two such builds take place simultaneously,
they may each look in the cache at nearly the same
time and both decide that f1.o
must be rebuilt and pushed into the shared cache directory,
then both decide that f2.o
must be rebuilt (and pushed into the shared cache directory),
then both decide that f3.o
must be rebuilt...
This won't cause any actual build problems--both
builds will succeed,
generate correct output files,
and populate the cache--but
it does represent wasted effort.
To alleviate such contention for the cache,
you can use the --random
command-line option
to tell SCons to build dependencies
in a random order:
% scons -Q --random
cc -o f3.o -c f3.c
cc -o f1.o -c f1.c
cc -o f5.o -c f5.c
cc -o f2.o -c f2.c
cc -o f4.o -c f4.c
cc -o prog f1.o f2.o f3.o f4.o f5.o
Multiple builds using the --random
option
will usually build their dependencies in different,
random orders,
which minimizes the chances for a lot of
contention for same-named files
in the shared cache directory.
Multiple simultaneous builds might still race to try to build
the same target file on occasion,
but long sequences of inefficient contention
should be rare.
Note, of course,
the --random
option
will cause the output that SCons prints
to be inconsistent from invocation to invocation,
which may be an issue when
trying to compare output from different build runs.
If you want to make sure dependencies will be built
in a random order without having to specify
the --random
on very command line,
you can use the SetOption
function to
set the random
option
within any SConscript
file:
SetOption('random', 1) Program('prog', ['f1.c', 'f2.c', 'f3.c', 'f4.c', 'f5.c'])
[5] Actually, the MD5 signature is used as the name of the file in the shared cache directory in which the contents are stored.
We've already seen how you can use the Alias
function to create a target named install
:
env = Environment() hello = env.Program('hello.c') env.Install('/usr/bin', hello) env.Alias('install', '/usr/bin')
You can then use this alias on the command line to tell SCons more naturally that you want to install files:
% scons -Q install
cc -o hello.o -c hello.c
cc -o hello hello.o
Install file: "hello" as "/usr/bin/hello"
Like other Builder
methods, though,
the Alias
method returns an object
representing the alias being built.
You can then use this object as input to anothother Builder
.
This is especially useful if you use such an object
as input to another call to the Alias
Builder
,
allowing you to create a hierarchy
of nested aliases:
env = Environment() p = env.Program('foo.c') l = env.Library('bar.c') env.Install('/usr/bin', p) env.Install('/usr/lib', l) ib = env.Alias('install-bin', '/usr/bin') il = env.Alias('install-lib', '/usr/lib') env.Alias('install', [ib, il])
This example defines separate install
,
install-bin
,
and install-lib
aliases,
allowing you finer control over what gets installed:
%scons -Q install-bin
cc -o foo.o -c foo.c cc -o foo foo.o Install file: "foo" as "/usr/bin/foo" %scons -Q install-lib
cc -o bar.o -c bar.c ar rc libbar.a bar.o ranlib libbar.a Install file: "libbar.a" as "/usr/lib/libbar.a" %scons -Q -c /
Removed foo.o Removed foo Removed /usr/bin/foo Removed bar.o Removed libbar.a Removed /usr/lib/libbar.a %scons -Q install
cc -o foo.o -c foo.c cc -o foo foo.o Install file: "foo" as "/usr/bin/foo" cc -o bar.o -c bar.c ar rc libbar.a bar.o ranlib libbar.a Install file: "libbar.a" as "/usr/lib/libbar.a"
So far, we've been using examples of building C and C++ programs to demonstrate the features of SCons. SCons also supports building Java programs, but Java builds are handled slightly differently, which reflects the ways in which the Java compiler and tools build programs differently than other languages' tool chains.
The basic activity when programming in Java,
of course, is to take one or more .java
files
containing Java source code
and to call the Java compiler
to turn them into one or more
.class
files.
In SCons, you do this
by giving the Java
Builder
a target directory in which
to put the .class
files,
and a source directory that contains
the .java
files:
Java('classes', 'src')
If the src
directory contains
three .java
source files,
then running SCons might look like this:
% scons -Q
javac -d classes -sourcepath src src/Example1.java src/Example2.java src/Example3.java
SCons will actually search the src
directory tree for all of the .java
files.
The Java compiler will then create the
necessary class files in the classes
subdirectory,
based on the class names found in the .java
files.
In addition to searching the source directory for
.java
files,
SCons actually runs the .java
files
through a stripped-down Java parser that figures out
what classes are defined.
In other words, SCons knows,
without you having to tell it,
what .class
files
will be produced by the javac call.
So our one-liner example from the preceding section:
Java('classes', 'src')
Will not only tell you reliably
that the .class
files
in the classes
subdirectory
are up-to-date:
%scons -Q
javac -d classes -sourcepath src src/Example1.java src/Example2.java src/Example3.java %scons -Q classes
scons: `classes' is up to date.
But it will also remove all of the generated
.class
files,
even for inner classes,
without you having to specify them manually.
For example, if our
Example1.java
and
Example3.java
files both define additional classes,
and the class defined in Example2.java
has an inner class,
running scons -c
will clean up all of those .class
files
as well:
%scons -Q
javac -d classes -sourcepath src src/Example1.java src/Example2.java src/Example3.java %scons -Q -c classes
Removed classes/Example1.class Removed classes/AdditionalClass1.class Removed classes/Example2$Inner2.class Removed classes/Example2.class Removed classes/Example3.class Removed classes/AdditionalClass3.class
To ensure correct handling of .class
dependencies in all cases, you need to tell SCons which Java
version is being used. This is needed because Java 1.5 changed
the .class
file names for nested anonymous
inner classes. Use the JAVAVERSION
construction
variable to specify the version in use. With Java 1.6, the
one-liner example can then be defined like this:
Java('classes', 'src', JAVAVERSION='1.6')
See JAVAVERSION
in the man page for more information.
After building the class files,
it's common to collect them into
a Java archive (.jar
) file,
which you do by calling the Jar
Builder method.
If you want to just collect all of the
class files within a subdirectory,
you can just specify that subdirectory
as the Jar
source:
Java(target = 'classes', source = 'src') Jar(target = 'test.jar', source = 'classes')
SCons will then pass that directory
to the jar command,
which will collect all of the underlying
.class
files:
% scons -Q
javac -d classes -sourcepath src src/Example1.java src/Example2.java src/Example3.java
jar cf test.jar classes
If you want to keep all of the
.class
files
for multiple programs in one location,
and only archive some of them in
each .jar
file,
you can pass the Jar
builder a
list of files as its source.
It's extremely simple to create multiple
.jar
files this way,
using the lists of target class files created
by calls to the Java
builder
as sources to the various Jar
calls:
prog1_class_files = Java(target = 'classes', source = 'prog1') prog2_class_files = Java(target = 'classes', source = 'prog2') Jar(target = 'prog1.jar', source = prog1_class_files) Jar(target = 'prog2.jar', source = prog2_class_files)
This will then create
prog1.jar
and prog2.jar
next to the subdirectories
that contain their .java
files:
% scons -Q
javac -d classes -sourcepath prog1 prog1/Example1.java prog1/Example2.java
javac -d classes -sourcepath prog2 prog2/Example3.java prog2/Example4.java
jar cf prog1.jar -C classes Example1.class -C classes Example2.class
jar cf prog2.jar -C classes Example3.class -C classes Example4.class
You can generate C header and source files
for implementing native methods,
by using the JavaH
Builder.
There are several ways of using the JavaH
Builder.
One typical invocation might look like:
classes = Java(target = 'classes', source = 'src/pkg/sub') JavaH(target = 'native', source = classes)
The source is a list of class files generated by the
call to the Java
Builder,
and the target is the output directory in
which we want the C header files placed.
The target
gets converted into the -d
when SCons runs javah:
% scons -Q
javac -d classes -sourcepath src/pkg/sub src/pkg/sub/Example1.java src/pkg/sub/Example2.java src/pkg/sub/Example3.java
javah -d native -classpath classes pkg.sub.Example1 pkg.sub.Example2 pkg.sub.Example3
In this case,
the call to javah
will generate the header files
native/pkg_sub_Example1.h
,
native/pkg_sub_Example2.h
and
native/pkg_sub_Example3.h
.
Notice that SCons remembered that the class
files were generated with a target directory of
classes
,
and that it then specified that target directory
as the -classpath
option
to the call to javah.
Although it's more convenient to use
the list of class files returned by
the Java
Builder
as the source of a call to the JavaH
Builder,
you can
specify the list of class files
by hand, if you prefer.
If you do,
you need to set the
$JAVACLASSDIR
construction variable
when calling JavaH
:
Java(target = 'classes', source = 'src/pkg/sub') class_file_list = ['classes/pkg/sub/Example1.class', 'classes/pkg/sub/Example2.class', 'classes/pkg/sub/Example3.class'] JavaH(target = 'native', source = class_file_list, JAVACLASSDIR = 'classes')
The $JAVACLASSDIR
value then
gets converted into the -classpath
when SCons runs javah:
% scons -Q
javac -d classes -sourcepath src/pkg/sub src/pkg/sub/Example1.java src/pkg/sub/Example2.java src/pkg/sub/Example3.java
javah -d native -classpath classes pkg.sub.Example1 pkg.sub.Example2 pkg.sub.Example3
Lastly, if you don't want a separate header file
generated for each source file,
you can specify an explicit File Node
as the target of the JavaH
Builder:
classes = Java(target = 'classes', source = 'src/pkg/sub') JavaH(target = File('native.h'), source = classes)
Because SCons assumes by default
that the target of the JavaH
builder is a directory,
you need to use the File
function
to make sure that SCons doesn't
create a directory named native.h
.
When a file is used, though,
SCons correctly converts the file name
into the javah -o
option:
% scons -Q
javac -d classes -sourcepath src/pkg/sub src/pkg/sub/Example1.java src/pkg/sub/Example2.java src/pkg/sub/Example3.java
javah -o native.h -classpath classes pkg.sub.Example1 pkg.sub.Example2 pkg.sub.Example3
You can generate Remote Method Invocation stubs
by using the RMIC
Builder.
The source is a list of directories,
typically returned by a call to the Java
Builder,
and the target is an output directory
where the _Stub.class
and _Skel.class
files will
be placed:
classes = Java(target = 'classes', source = 'src/pkg/sub') RMIC(target = 'outdir', source = classes)
As it did with the JavaH
Builder,
SCons remembers the class directory
and passes it as the -classpath
option
to rmic:
% scons -Q
javac -d classes -sourcepath src/pkg/sub src/pkg/sub/Example1.java src/pkg/sub/Example2.java
rmic -d outdir -classpath classes pkg.sub.Example1 pkg.sub.Example2
This example would generate the files
outdir/pkg/sub/Example1_Skel.class
,
outdir/pkg/sub/Example1_Stub.class
,
outdir/pkg/sub/Example2_Skel.class
and
outdir/pkg/sub/Example2_Stub.class
.
SCons supports a lot of additional functionality that doesn't readily fit into the other chapters.
Although the SCons code itself will run
on any 2.x Python version 2.7 or later,
you are perfectly free to make use of
Python syntax and modules from later versions
when writing your SConscript
files
or your own local modules.
If you do this, it's usually helpful to
configure SCons to exit gracefully with an error message
if it's being run with a version of Python
that simply won't work with your code.
This is especially true if you're going to use SCons
to build source code that you plan to distribute publicly,
where you can't be sure of the Python version
that an anonymous remote user might use
to try to build your software.
SCons provides an EnsurePythonVersion
function for this.
You simply pass it the major and minor versions
numbers of the version of Python you require:
EnsurePythonVersion(2, 5)
And then SCons will exit with the following error message when a user runs it with an unsupported earlier version of Python:
% scons -Q
Python 2.5 or greater required, but you have Python 2.3.6
You may, of course, write your SConscript
files
to use features that were only added in
recent versions of SCons.
When you publicly distribute software that is built using SCons,
it's helpful to have SCons
verify the version being used and
exit gracefully with an error message
if the user's version of SCons won't work
with your SConscript
files.
SCons provides an EnsureSConsVersion
function
that verifies the version of SCons
in the same
the EnsurePythonVersion
function
verifies the version of Python,
by passing in the major and minor versions
numbers of the version of SCons you require:
EnsureSConsVersion(1, 0)
And then SCons will exit with the following error message when a user runs it with an unsupported earlier version of SCons:
% scons -Q
SCons 1.0 or greater required, but you have SCons 0.98.5
SCons supports an Exit
function
which can be used to terminate SCons
while reading the SConscript
files,
usually because you've detected a condition
under which it doesn't make sense to proceed:
if ARGUMENTS.get('FUTURE'): print("The FUTURE option is not supported yet!") Exit(2) env = Environment() env.Program('hello.c')
%scons -Q FUTURE=1
The FUTURE option is not supported yet! %scons -Q
cc -o hello.o -c hello.c cc -o hello hello.o
The Exit
function takes as an argument
the (numeric) exit status that you want SCons to exit with.
If you don't specify a value,
the default is to exit with 0
,
which indicates successful execution.
Note that the Exit
function
is equivalent to calling the Python
sys.exit
function
(which the it actually calls),
but because Exit
is a SCons function,
you don't have to import the Python
sys
module to use it.
The FindFile
function searches for a file in a list of directories.
If there is only one directory, it can be given as a simple string.
The function returns a File node if a matching file exists,
or None if no file is found.
(See the documentation for the Glob
function for an alternative way
of searching for entries in a directory.)
# one directory print("%s"%FindFile('missing', '.')) t = FindFile('exists', '.') print("%s %s"%(t.__class__, t))
% scons -Q
None
<class 'SCons.Node.FS.File'> exists
scons: `.' is up to date.
# several directories includes = [ '.', 'include', 'src/include'] headers = [ 'nonesuch.h', 'config.h', 'private.h', 'dist.h'] for hdr in headers: print('%-12s: %s'%(hdr, FindFile(hdr, includes)))
% scons -Q
nonesuch.h : None
config.h : config.h
private.h : src/include/private.h
dist.h : include/dist.h
scons: `.' is up to date.
If the file exists in more than one directory, only the first occurrence is returned.
print(FindFile('multiple', ['sub1', 'sub2', 'sub3'])) print(FindFile('multiple', ['sub2', 'sub3', 'sub1'])) print(FindFile('multiple', ['sub3', 'sub1', 'sub2']))
% scons -Q
sub1/multiple
sub2/multiple
sub3/multiple
scons: `.' is up to date.
In addition to existing files, FindFile
will also find derived files
(that is, non-leaf files) that haven't been built yet.
(Leaf files should already exist, or the build will fail!)
# Neither file exists, so build will fail Command('derived', 'leaf', 'cat >$TARGET $SOURCE') print(FindFile('leaf', '.')) print(FindFile('derived', '.'))
% scons -Q
leaf
derived
cat > derived leaf
# Only 'leaf' exists Command('derived', 'leaf', 'cat >$TARGET $SOURCE') print(FindFile('leaf', '.')) print(FindFile('derived', '.'))
% scons -Q
leaf
derived
cat > derived leaf
If a source file exists, FindFile
will correctly return the name
in the build directory.
# Only 'src/leaf' exists VariantDir('build', 'src') print(FindFile('leaf', 'build'))
% scons -Q
build/leaf
scons: `.' is up to date.
SCons supports a Flatten
function
which takes an input Python sequence
(list or tuple)
and returns a flattened list
containing just the individual elements of
the sequence.
This can be handy when trying to examine
a list composed of the lists
returned by calls to various Builders.
For example, you might collect
object files built in different ways
into one call to the Program
Builder
by just enclosing them in a list, as follows:
objects = [ Object('prog1.c'), Object('prog2.c', CCFLAGS='-DFOO'), ] Program(objects)
Because the Builder calls in SCons flatten their input lists, this works just fine to build the program:
% scons -Q
cc -o prog1.o -c prog1.c
cc -o prog2.o -c -DFOO prog2.c
cc -o prog1 prog1.o prog2.o
But if you were debugging your build
and wanted to print the absolute path
of each object file in the
objects
list,
you might try the following simple approach,
trying to print each Node's
abspath
attribute:
objects = [ Object('prog1.c'), Object('prog2.c', CCFLAGS='-DFOO'), ] Program(objects) for object_file in objects: print(object_file.abspath)
This does not work as expected
because each call to str
is operating an embedded list returned by
each Object
call,
not on the underlying Nodes within those lists:
% scons -Q
AttributeError: 'NodeList' object has no attribute 'abspath':
File "/home/my/project/SConstruct", line 8:
print(object_file.abspath)
The solution is to use the Flatten
function
so that you can pass each Node to
the str
separately:
objects = [ Object('prog1.c'), Object('prog2.c', CCFLAGS='-DFOO'), ] Program(objects) for object_file in Flatten(objects): print(object_file.abspath)
% scons -Q
/home/me/project/prog1.o
/home/me/project/prog2.o
cc -o prog1.o -c prog1.c
cc -o prog2.o -c -DFOO prog2.c
cc -o prog1 prog1.o prog2.o
If you need to find the directory from
which the user invoked the scons
command,
you can use the GetLaunchDir
function:
env = Environment( LAUNCHDIR = GetLaunchDir(), ) env.Command('directory_build_info', '$LAUNCHDIR/build_info' Copy('$TARGET', '$SOURCE'))
Because SCons is usually invoked from the top-level
directory in which the SConstruct
file lives,
the Python os.getcwd()
is often equivalent.
However, the SCons
-u
,
-U
and
-D
command-line options,
when invoked from a subdirectory,
will cause SCons to change to the directory
in which the SConstruct
file is found.
When those options are used,
GetLaunchDir
will still return the path to the
user's invoking subdirectory,
allowing the SConscript
configuration
to still get at configuration (or other) files
from the originating directory.
The experience of configuring any software build tool to build a large code base usually, at some point, involves trying to figure out why the tool is behaving a certain way, and how to get it to behave the way you want. SCons is no different. This appendix contains a number of different ways in which you can get some additional insight into SCons' behavior.
Note that we're always interested in trying to improve how you can troubleshoot configuration problems. If you run into a problem that has you scratching your head, and which there just doesn't seem to be a good way to debug, odds are pretty good that someone else will run into the same problem, too. If so, please let the SCons development team know (preferably by filing a bug report or feature request at our project pages at tigris.org) so that we can use your feedback to try to come up with a better way to help you, and others, get the necessary insight into SCons behavior to help identify and fix configuration issues.
Let's look at a simple example of a misconfigured build that causes a target to be rebuilt every time SCons is run:
# Intentionally misspell the output file name in the # command used to create the file: Command('file.out', 'file.in', 'cp $SOURCE file.oout')
(Note to Windows users: The POSIX cp command
copies the first file named on the command line
to the second file.
In our example, it copies the file.in
file
to the file.out
file.)
Now if we run SCons multiple times on this example, we see that it re-runs the cp command every time:
%scons -Q
cp file.in file.oout %scons -Q
cp file.in file.oout %scons -Q
cp file.in file.oout
In this example,
the underlying cause is obvious:
we've intentionally misspelled the output file name
in the cp command,
so the command doesn't actually
build the file.out
file that we've told SCons to expect.
But if the problem weren't obvious,
it would be helpful
to specify the --debug=explain
option
on the command line
to have SCons tell us very specifically
why it's decided to rebuild the target:
% scons -Q --debug=explain
scons: building `file.out' because it doesn't exist
cp file.in file.oout
If this had been a more complicated example involving a lot of build output, having SCons tell us that it's trying to rebuild the target file because it doesn't exist would be an important clue that something was wrong with the command that we invoked to build it.
Note that you can also use --warn=target-not-built which checks whether or not expected targets exist after a build rule is executed.
% scons -Q --warn=target-not-built
cp file.in file.oout
scons: warning: Cannot find target file.out after building
File "/Users/bdbaddog/devel/scons/git/as_scons/bootstrap/src/script/scons.py", line 201, in <module>
The --debug=explain
option also comes in handy
to help figure out what input file changed.
Given a simple configuration that builds
a program from three source files,
changing one of the source files
and rebuilding with the --debug=explain
option shows very specifically
why SCons rebuilds the files that it does:
%scons -Q
cc -o file1.o -c file1.c cc -o file2.o -c file2.c cc -o file3.o -c file3.c cc -o prog file1.o file2.o file3.o % [CHANGE THE CONTENTS OF file2.c] %scons -Q --debug=explain
scons: rebuilding `file2.o' because `file2.c' changed cc -o file2.o -c file2.c scons: rebuilding `prog' because `file2.o' changed cc -o prog file1.o file2.o file3.o
This becomes even more helpful
in identifying when a file is rebuilt
due to a change in an implicit dependency,
such as an incuded .h
file.
If the file1.c
and file3.c
files
in our example
both included a hello.h
file,
then changing that included file
and re-running SCons with the --debug=explain
option
will pinpoint that it's the change to the included file
that starts the chain of rebuilds:
%scons -Q
cc -o file1.o -c -I. file1.c cc -o file2.o -c -I. file2.c cc -o file3.o -c -I. file3.c cc -o prog file1.o file2.o file3.o % [CHANGE THE CONTENTS OF hello.h] %scons -Q --debug=explain
scons: rebuilding `file1.o' because `hello.h' changed cc -o file1.o -c -I. file1.c scons: rebuilding `file3.o' because `hello.h' changed cc -o file3.o -c -I. file3.c scons: rebuilding `prog' because: `file1.o' changed `file3.o' changed cc -o prog file1.o file2.o file3.o
(Note that the --debug=explain
option will only tell you
why SCons decided to rebuild necessary targets.
It does not tell you what files it examined
when deciding not
to rebuild a target file,
which is often a more valuable question to answer.)
When you create a construction environment,
SCons populates it
with construction variables that are set up
for various compilers, linkers and utilities
that it finds on your system.
Although this is usually helpful and what you want,
it might be frustrating if SCons
doesn't set certain variables that you
expect to be set.
In situations like this,
it's sometimes helpful to use the
construction environment Dump
method
to print all or some of
the construction variables.
Note that the Dump
method
returns
the representation of the variables
in the environment
for you to print (or otherwise manipulate):
env = Environment() print env.Dump()
On a POSIX system with gcc installed, this might generate:
% scons
scons: Reading SConscript files ...
{ 'BUILDERS': {'_InternalInstall': <function InstallBuilderWrapper at 0x700000>, '_InternalInstallVersionedLib': <function InstallVersionedBuilderWrapper at 0x700000>, '_InternalInstallAs': <function InstallAsBuilderWrapper at 0x700000>},
'CONFIGUREDIR': '#/.sconf_temp',
'CONFIGURELOG': '#/config.log',
'CPPSUFFIXES': [ '.c',
'.C',
'.cxx',
'.cpp',
'.c++',
'.cc',
'.h',
'.H',
'.hxx',
'.hpp',
'.hh',
'.F',
'.fpp',
'.FPP',
'.m',
'.mm',
'.S',
'.spp',
'.SPP',
'.sx'],
'DSUFFIXES': ['.d'],
'Dir': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'Dirs': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'ENV': { 'PATH': '/usr/local/bin:/opt/bin:/bin:/usr/bin'},
'ESCAPE': <function escape at 0x700000>,
'File': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'HOST_ARCH': None,
'HOST_OS': None,
'IDLSUFFIXES': ['.idl', '.IDL'],
'INSTALL': <function copyFunc at 0x700000>,
'INSTALLVERSIONEDLIB': <function copyFuncVersionedLib at 0x700000>,
'LIBPREFIX': 'lib',
'LIBPREFIXES': ['$LIBPREFIX'],
'LIBSUFFIX': '.a',
'LIBSUFFIXES': ['$LIBSUFFIX', '$SHLIBSUFFIX'],
'MAXLINELENGTH': 128072,
'OBJPREFIX': '',
'OBJSUFFIX': '.o',
'PLATFORM': 'posix',
'PROGPREFIX': '',
'PROGSUFFIX': '',
'PSPAWN': <function piped_env_spawn at 0x700000>,
'RDirs': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'SCANNERS': [<SCons.Scanner.Base object at 0x700000>],
'SHELL': 'sh',
'SHLIBPREFIX': '$LIBPREFIX',
'SHLIBSUFFIX': '.so',
'SHOBJPREFIX': '$OBJPREFIX',
'SHOBJSUFFIX': '$OBJSUFFIX',
'SPAWN': <function subprocess_spawn at 0x700000>,
'TARGET_ARCH': None,
'TARGET_OS': None,
'TEMPFILE': <class 'SCons.Platform.TempFileMunge'>,
'TEMPFILEPREFIX': '@',
'TOOLS': ['install', 'install'],
'_CPPDEFFLAGS': '${_defines(CPPDEFPREFIX, CPPDEFINES, CPPDEFSUFFIX, __env__)}',
'_CPPINCFLAGS': '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)',
'_LIBDIRFLAGS': '$( ${_concat(LIBDIRPREFIX, LIBPATH, LIBDIRSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)',
'_LIBFLAGS': '${_concat(LIBLINKPREFIX, LIBS, LIBLINKSUFFIX, __env__)}',
'__DRPATH': '$_DRPATH',
'__DSHLIBVERSIONFLAGS': '${__libversionflags(__env__,"DSHLIBVERSION","_DSHLIBVERSIONFLAGS")}',
'__LDMODULEVERSIONFLAGS': '${__libversionflags(__env__,"LDMODULEVERSION","_LDMODULEVERSIONFLAGS")}',
'__RPATH': '$_RPATH',
'__SHLIBVERSIONFLAGS': '${__libversionflags(__env__,"SHLIBVERSION","_SHLIBVERSIONFLAGS")}',
'__libversionflags': <function __libversionflags at 0x700000>,
'_concat': <function _concat at 0x700000>,
'_defines': <function _defines at 0x700000>,
'_stripixes': <function _stripixes at 0x700000>}
scons: done reading SConscript files.
scons: Building targets ...
scons: `.' is up to date.
scons: done building targets.
On a Windows system with Visual C++ the output might look like:
C:\>scons
scons: Reading SConscript files ...
{ 'BUILDERS': {'_InternalInstallVersionedLib': <function InstallVersionedBuilderWrapper at 0x700000>, '_InternalInstall': <function InstallBuilderWrapper at 0x700000>, 'Object': <SCons.Builder.CompositeBuilder object at 0x700000>, 'PCH': <SCons.Builder.BuilderBase object at 0x700000>, 'RES': <SCons.Builder.BuilderBase object at 0x700000>, 'SharedObject': <SCons.Builder.CompositeBuilder object at 0x700000>, 'StaticObject': <SCons.Builder.CompositeBuilder object at 0x700000>, '_InternalInstallAs': <function InstallAsBuilderWrapper at 0x700000>},
'CC': 'cl',
'CCCOM': <SCons.Action.FunctionAction object at 0x700000>,
'CCFLAGS': ['/nologo'],
'CCPCHFLAGS': ['${(PCH and "/Yu%s \\"/Fp%s\\""%(PCHSTOP or "",File(PCH))) or ""}'],
'CCPDBFLAGS': ['${(PDB and "/Z7") or ""}'],
'CFILESUFFIX': '.c',
'CFLAGS': [],
'CONFIGUREDIR': '#/.sconf_temp',
'CONFIGURELOG': '#/config.log',
'CPPDEFPREFIX': '/D',
'CPPDEFSUFFIX': '',
'CPPSUFFIXES': [ '.c',
'.C',
'.cxx',
'.cpp',
'.c++',
'.cc',
'.h',
'.H',
'.hxx',
'.hpp',
'.hh',
'.F',
'.fpp',
'.FPP',
'.m',
'.mm',
'.S',
'.spp',
'.SPP',
'.sx'],
'CXX': '$CC',
'CXXCOM': '${TEMPFILE("$CXX $_MSVC_OUTPUT_FLAG /c $CHANGED_SOURCES $CXXFLAGS $CCFLAGS $_CCCOMCOM","$CXXCOMSTR")}',
'CXXFILESUFFIX': '.cc',
'CXXFLAGS': ['$(', '/TP', '$)'],
'DSUFFIXES': ['.d'],
'Dir': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'Dirs': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'ENV': { 'PATH': 'C:\\WINDOWS\\System32',
'PATHEXT': '.COM;.EXE;.BAT;.CMD',
'SystemRoot': 'C:\\WINDOWS'},
'ESCAPE': <function escape at 0x700000>,
'File': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'HOST_ARCH': '',
'HOST_OS': 'win32',
'IDLSUFFIXES': ['.idl', '.IDL'],
'INCPREFIX': '/I',
'INCSUFFIX': '',
'INSTALL': <function copyFunc at 0x700000>,
'INSTALLVERSIONEDLIB': <function copyFuncVersionedLib at 0x700000>,
'LIBPREFIX': '',
'LIBPREFIXES': ['$LIBPREFIX'],
'LIBSUFFIX': '.lib',
'LIBSUFFIXES': ['$LIBSUFFIX'],
'MAXLINELENGTH': 2048,
'MSVC_SETUP_RUN': True,
'OBJPREFIX': '',
'OBJSUFFIX': '.obj',
'PCHCOM': '$CXX /Fo${TARGETS[1]} $CXXFLAGS $CCFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS /c $SOURCES /Yc$PCHSTOP /Fp${TARGETS[0]} $CCPDBFLAGS $PCHPDBFLAGS',
'PCHPDBFLAGS': ['${(PDB and "/Yd") or ""}'],
'PLATFORM': 'win32',
'PROGPREFIX': '',
'PROGSUFFIX': '.exe',
'PSPAWN': <function piped_spawn at 0x700000>,
'RC': 'rc',
'RCCOM': <SCons.Action.FunctionAction object at 0x700000>,
'RCFLAGS': [],
'RCSUFFIXES': ['.rc', '.rc2'],
'RDirs': <SCons.Defaults.Variable_Method_Caller object at 0x700000>,
'SCANNERS': [<SCons.Scanner.Base object at 0x700000>],
'SHCC': '$CC',
'SHCCCOM': <SCons.Action.FunctionAction object at 0x700000>,
'SHCCFLAGS': ['$CCFLAGS'],
'SHCFLAGS': ['$CFLAGS'],
'SHCXX': '$CXX',
'SHCXXCOM': '${TEMPFILE("$SHCXX $_MSVC_OUTPUT_FLAG /c $CHANGED_SOURCES $SHCXXFLAGS $SHCCFLAGS $_CCCOMCOM","$SHCXXCOMSTR")}',
'SHCXXFLAGS': ['$CXXFLAGS'],
'SHELL': 'command',
'SHLIBPREFIX': '',
'SHLIBSUFFIX': '.dll',
'SHOBJPREFIX': '$OBJPREFIX',
'SHOBJSUFFIX': '$OBJSUFFIX',
'SPAWN': <function spawn at 0x700000>,
'STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME': 1,
'TARGET_ARCH': None,
'TARGET_OS': None,
'TEMPFILE': <class 'SCons.Platform.TempFileMunge'>,
'TEMPFILEPREFIX': '@',
'TOOLS': ['msvc', 'install', 'install'],
'_CCCOMCOM': '$CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS $CCPCHFLAGS $CCPDBFLAGS',
'_CPPDEFFLAGS': '${_defines(CPPDEFPREFIX, CPPDEFINES, CPPDEFSUFFIX, __env__)}',
'_CPPINCFLAGS': '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)',
'_LIBDIRFLAGS': '$( ${_concat(LIBDIRPREFIX, LIBPATH, LIBDIRSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)',
'_LIBFLAGS': '${_concat(LIBLINKPREFIX, LIBS, LIBLINKSUFFIX, __env__)}',
'_MSVC_OUTPUT_FLAG': <function msvc_output_flag at 0x700000>,
'__DSHLIBVERSIONFLAGS': '${__libversionflags(__env__,"DSHLIBVERSION","_DSHLIBVERSIONFLAGS")}',
'__LDMODULEVERSIONFLAGS': '${__libversionflags(__env__,"LDMODULEVERSION","_LDMODULEVERSIONFLAGS")}',
'__SHLIBVERSIONFLAGS': '${__libversionflags(__env__,"SHLIBVERSION","_SHLIBVERSIONFLAGS")}',
'__libversionflags': <function __libversionflags at 0x700000>,
'_concat': <function _concat at 0x700000>,
'_defines': <function _defines at 0x700000>,
'_stripixes': <function _stripixes at 0x700000>}
scons: done reading SConscript files.
scons: Building targets ...
scons: `.' is up to date.
scons: done building targets.
The construction environments in these examples have actually been restricted to just gcc and Visual C++, respectively. In a real-life situation, the construction environments will likely contain a great many more variables. Also note that we've massaged the example output above to make the memory address of all objects a constant 0x700000. In reality, you would see a different hexadecimal number for each object.
To make it easier to see just what you're
interested in,
the Dump
method allows you to
specify a specific constrcution variable
that you want to disply.
For example,
it's not unusual to want to verify
the external environment used to execute build commands,
to make sure that the PATH and other
environment variables are set up the way they should be.
You can do this as follows:
env = Environment() print env.Dump('ENV')
Which might display the following when executed on a POSIX system:
% scons
scons: Reading SConscript files ...
{ 'PATH': '/usr/local/bin:/opt/bin:/bin:/usr/bin'}
scons: done reading SConscript files.
scons: Building targets ...
scons: `.' is up to date.
scons: done building targets.
And the following when executed on a Windows system:
C:\>scons
scons: Reading SConscript files ...
{ 'PATH': 'C:\\WINDOWS\\System32',
'PATHEXT': '.COM;.EXE;.BAT;.CMD',
'SystemRoot': 'C:\\WINDOWS'}
scons: done reading SConscript files.
scons: Building targets ...
scons: `.' is up to date.
scons: done building targets.
Sometimes the best way to try to figure out what
SCons is doing is simply to take a look at the
dependency graph that it constructs
based on your SConscript
files.
The --tree
option
will display all or part of the
SCons dependency graph in an
"ASCII art" graphical format
that shows the dependency hierarchy.
For example, given the following input SConstruct
file:
env = Environment(CPPPATH = ['.']) env.Program('prog', ['f1.c', 'f2.c', 'f3.c'])
Running SCons with the --tree=all
option yields:
% scons -Q --tree=all
cc -o f1.o -c -I. f1.c
cc -o f2.o -c -I. f2.c
cc -o f3.o -c -I. f3.c
cc -o prog f1.o f2.o f3.o
+-.
+-SConstruct
+-f1.c
+-f1.o
| +-f1.c
| +-inc.h
+-f2.c
+-f2.o
| +-f2.c
| +-inc.h
+-f3.c
+-f3.o
| +-f3.c
| +-inc.h
+-inc.h
+-prog
+-f1.o
| +-f1.c
| +-inc.h
+-f2.o
| +-f2.c
| +-inc.h
+-f3.o
+-f3.c
+-inc.h
The tree will also be printed when the
-n
(no execute) option is used,
which allows you to examine the dependency graph
for a configuration without actually
rebuilding anything in the tree.
The --tree
option only prints
the dependency graph for the specified targets
(or the default target(s) if none are specified on the command line).
So if you specify a target like f2.o
on the command line,
the --tree
option will only
print the dependency graph for that file:
% scons -Q --tree=all f2.o
cc -o f2.o -c -I. f2.c
+-f2.o
+-f2.c
+-inc.h
This is, of course, useful for restricting the output from a very large build configuration to just a portion in which you're interested. Multiple targets are fine, in which case a tree will be printed for each specified target:
% scons -Q --tree=all f1.o f3.o
cc -o f1.o -c -I. f1.c
+-f1.o
+-f1.c
+-inc.h
cc -o f3.o -c -I. f3.c
+-f3.o
+-f3.c
+-inc.h
The status
argument may be used
to tell SCons to print status information about
each file in the dependency graph:
% scons -Q --tree=status
cc -o f1.o -c -I. f1.c
cc -o f2.o -c -I. f2.c
cc -o f3.o -c -I. f3.c
cc -o prog f1.o f2.o f3.o
E = exists
R = exists in repository only
b = implicit builder
B = explicit builder
S = side effect
P = precious
A = always build
C = current
N = no clean
H = no cache
[E b ]+-.
[E C ] +-SConstruct
[E C ] +-f1.c
[E B C ] +-f1.o
[E C ] | +-f1.c
[E C ] | +-inc.h
[E C ] +-f2.c
[E B C ] +-f2.o
[E C ] | +-f2.c
[E C ] | +-inc.h
[E C ] +-f3.c
[E B C ] +-f3.o
[E C ] | +-f3.c
[E C ] | +-inc.h
[E C ] +-inc.h
[E B C ] +-prog
[E B C ] +-f1.o
[E C ] | +-f1.c
[E C ] | +-inc.h
[E B C ] +-f2.o
[E C ] | +-f2.c
[E C ] | +-inc.h
[E B C ] +-f3.o
[E C ] +-f3.c
[E C ] +-inc.h
Note that --tree=all,status
is equivalent;
the all
is assumed if only status
is present.
As an alternative to all
,
you can specify --tree=derived
to have SCons only print derived targets
in the tree output,
skipping source files
(like .c
and .h
files):
% scons -Q --tree=derived
cc -o f1.o -c -I. f1.c
cc -o f2.o -c -I. f2.c
cc -o f3.o -c -I. f3.c
cc -o prog f1.o f2.o f3.o
+-.
+-f1.o
+-f2.o
+-f3.o
+-prog
+-f1.o
+-f2.o
+-f3.o
You can use the status
modifier with derived
as well:
% scons -Q --tree=derived,status
cc -o f1.o -c -I. f1.c
cc -o f2.o -c -I. f2.c
cc -o f3.o -c -I. f3.c
cc -o prog f1.o f2.o f3.o
E = exists
R = exists in repository only
b = implicit builder
B = explicit builder
S = side effect
P = precious
A = always build
C = current
N = no clean
H = no cache
[E b ]+-.
[E B C ] +-f1.o
[E B C ] +-f2.o
[E B C ] +-f3.o
[E B C ] +-prog
[E B C ] +-f1.o
[E B C ] +-f2.o
[E B C ] +-f3.o
Note that the order of the --tree=
arguments doesn't matter;
--tree=status,derived
is
completely equivalent.
The default behavior of the --tree
option
is to repeat all of the dependencies each time the library dependency
(or any other dependency file) is encountered in the tree.
If certain target files share other target files,
such as two programs that use the same library:
env = Environment(CPPPATH = ['.'], LIBS = ['foo'], LIBPATH = ['.']) env.Library('foo', ['f1.c', 'f2.c', 'f3.c']) env.Program('prog1.c') env.Program('prog2.c')
Then there can be a lot of repetition in the
--tree=
output:
% scons -Q --tree=all
cc -o f1.o -c -I. f1.c
cc -o f2.o -c -I. f2.c
cc -o f3.o -c -I. f3.c
ar rc libfoo.a f1.o f2.o f3.o
ranlib libfoo.a
cc -o prog1.o -c -I. prog1.c
cc -o prog1 prog1.o -L. -lfoo
cc -o prog2.o -c -I. prog2.c
cc -o prog2 prog2.o -L. -lfoo
+-.
+-SConstruct
+-f1.c
+-f1.o
| +-f1.c
| +-inc.h
+-f2.c
+-f2.o
| +-f2.c
| +-inc.h
+-f3.c
+-f3.o
| +-f3.c
| +-inc.h
+-inc.h
+-libfoo.a
| +-f1.o
| | +-f1.c
| | +-inc.h
| +-f2.o
| | +-f2.c
| | +-inc.h
| +-f3.o
| +-f3.c
| +-inc.h
+-prog1
| +-prog1.o
| | +-prog1.c
| | +-inc.h
| +-libfoo.a
| +-f1.o
| | +-f1.c
| | +-inc.h
| +-f2.o
| | +-f2.c
| | +-inc.h
| +-f3.o
| +-f3.c
| +-inc.h
+-prog1.c
+-prog1.o
| +-prog1.c
| +-inc.h
+-prog2
| +-prog2.o
| | +-prog2.c
| | +-inc.h
| +-libfoo.a
| +-f1.o
| | +-f1.c
| | +-inc.h
| +-f2.o
| | +-f2.c
| | +-inc.h
| +-f3.o
| +-f3.c
| +-inc.h
+-prog2.c
+-prog2.o
+-prog2.c
+-inc.h
In a large configuration with many internal libraries
and include files,
this can very quickly lead to huge output trees.
To help make this more manageable,
a prune
modifier may
be added to the option list,
in which case SCons
will print the name of a target that has
already been visited during the tree-printing
in [square brackets]
as an indication that the dependencies
of the target file may be found
by looking farther up the tree:
% scons -Q --tree=prune
cc -o f1.o -c -I. f1.c
cc -o f2.o -c -I. f2.c
cc -o f3.o -c -I. f3.c
ar rc libfoo.a f1.o f2.o f3.o
ranlib libfoo.a
cc -o prog1.o -c -I. prog1.c
cc -o prog1 prog1.o -L. -lfoo
cc -o prog2.o -c -I. prog2.c
cc -o prog2 prog2.o -L. -lfoo
+-.
+-SConstruct
+-f1.c
+-f1.o
| +-f1.c
| +-inc.h
+-f2.c
+-f2.o
| +-f2.c
| +-inc.h
+-f3.c
+-f3.o
| +-f3.c
| +-inc.h
+-inc.h
+-libfoo.a
| +-[f1.o]
| +-[f2.o]
| +-[f3.o]
+-prog1
| +-prog1.o
| | +-prog1.c
| | +-inc.h
| +-[libfoo.a]
+-prog1.c
+-[prog1.o]
+-prog2
| +-prog2.o
| | +-prog2.c
| | +-inc.h
| +-[libfoo.a]
+-prog2.c
+-[prog2.o]
Like the status
keyword,
the prune
argument by itself
is equivalent to --tree=all,prune
.
Sometimes it's useful to look at the
pre-substitution string
that SCons uses to generate
the command lines it executes.
This can be done with the --debug=presub
option:
% scons -Q --debug=presub
Building prog.o with action:
$CC -o $TARGET -c $CFLAGS $CCFLAGS $_CCOMCOM $SOURCES
cc -o prog.o -c -I. prog.c
Building prog with action:
$SMART_LINKCOM
cc -o prog prog.o
To get some insight into what library names
SCons is searching for,
and in which directories it is searching,
Use the --debug=findlibs
option.
Given the following input SConstruct
file:
env = Environment(LIBPATH = ['libs1', 'libs2']) env.Program('prog.c', LIBS=['foo', 'bar'])
And the libraries libfoo.a
and libbar.a
in libs1
and libs2
,
respectively,
use of the --debug=findlibs
option yields:
% scons -Q --debug=findlibs
findlibs: looking for 'libfoo.a' in 'libs1' ...
findlibs: ... FOUND 'libfoo.a' in 'libs1'
findlibs: looking for 'libfoo.so' in 'libs1' ...
findlibs: looking for 'libfoo.so' in 'libs2' ...
findlibs: looking for 'libbar.a' in 'libs1' ...
findlibs: looking for 'libbar.a' in 'libs2' ...
findlibs: ... FOUND 'libbar.a' in 'libs2'
findlibs: looking for 'libbar.so' in 'libs1' ...
findlibs: looking for 'libbar.so' in 'libs2' ...
cc -o prog.o -c prog.c
cc -o prog prog.o -Llibs1 -Llibs2 -lfoo -lbar
In general, SCons tries to keep its error messages short and informative. That means we usually try to avoid showing the stack traces that are familiar to experienced Python programmers, since they usually contain much more information than is useful to most people.
For example, the following SConstruct
file:
Program('prog.c')
Generates the following error if the
prog.c
file
does not exist:
% scons -Q
scons: *** [prog.o] Source `prog.c' not found, needed by target `prog.o'.
In this case,
the error is pretty obvious.
But if it weren't,
and you wanted to try to get more information
about the error,
the --debug=stacktrace
option
would show you exactly where in the SCons source code
the problem occurs:
% scons -Q --debug=stacktrace
scons: *** [prog.o] Source `prog.c' not found, needed by target `prog.o'.
scons: internal stack trace:
File "bootstrap/src/engine/SCons/Job.py", line 199, in start
task.prepare()
File "bootstrap/src/engine/SCons/Script/Main.py", line 175, in prepare
return SCons.Taskmaster.OutOfDateTask.prepare(self)
File "bootstrap/src/engine/SCons/Taskmaster.py", line 198, in prepare
executor.prepare()
File "bootstrap/src/engine/SCons/Executor.py", line 430, in prepare
raise SCons.Errors.StopError(msg % (s, self.batches[0].targets[0]))
Of course, if you do need to dive into the SCons source code, we'd like to know if, or how, the error messages or troubleshooting options could have been improved to avoid that. Not everyone has the necessary time or Python skill to dive into the source code, and we'd like to improve SCons for those people as well...
The internal SCons subsystem that handles walking
the dependency graph
and controls the decision-making about what to rebuild
is the Taskmaster
.
SCons supports a --taskmastertrace
option that tells the Taskmaster to print
information about the children (dependencies)
of the various Nodes on its walk down the graph,
which specific dependent Nodes are being evaluated,
and in what order.
The --taskmastertrace
option
takes as an argument the name of a file in
which to put the trace output,
with -
(a single hyphen)
indicating that the trace messages
should be printed to the standard output:
env = Environment(CPPPATH = ['.']) env.Program('prog.c')
% scons -Q --taskmastertrace=- prog
Taskmaster: Looking for a node to evaluate
Taskmaster: Considering node <no_state 0 'prog'> and its children:
Taskmaster: <no_state 0 'prog.o'>
Taskmaster: adjusted ref count: <pending 1 'prog'>, child 'prog.o'
Taskmaster: Considering node <no_state 0 'prog.o'> and its children:
Taskmaster: <no_state 0 'prog.c'>
Taskmaster: <no_state 0 'inc.h'>
Taskmaster: adjusted ref count: <pending 1 'prog.o'>, child 'prog.c'
Taskmaster: adjusted ref count: <pending 2 'prog.o'>, child 'inc.h'
Taskmaster: Considering node <no_state 0 'prog.c'> and its children:
Taskmaster: Evaluating <pending 0 'prog.c'>
Task.make_ready_current(): node <pending 0 'prog.c'>
Task.prepare(): node <up_to_date 0 'prog.c'>
Task.executed_with_callbacks(): node <up_to_date 0 'prog.c'>
Task.postprocess(): node <up_to_date 0 'prog.c'>
Task.postprocess(): removing <up_to_date 0 'prog.c'>
Task.postprocess(): adjusted parent ref count <pending 1 'prog.o'>
Taskmaster: Looking for a node to evaluate
Taskmaster: Considering node <no_state 0 'inc.h'> and its children:
Taskmaster: Evaluating <pending 0 'inc.h'>
Task.make_ready_current(): node <pending 0 'inc.h'>
Task.prepare(): node <up_to_date 0 'inc.h'>
Task.executed_with_callbacks(): node <up_to_date 0 'inc.h'>
Task.postprocess(): node <up_to_date 0 'inc.h'>
Task.postprocess(): removing <up_to_date 0 'inc.h'>
Task.postprocess(): adjusted parent ref count <pending 0 'prog.o'>
Taskmaster: Looking for a node to evaluate
Taskmaster: Considering node <pending 0 'prog.o'> and its children:
Taskmaster: <up_to_date 0 'prog.c'>
Taskmaster: <up_to_date 0 'inc.h'>
Taskmaster: Evaluating <pending 0 'prog.o'>
Task.make_ready_current(): node <pending 0 'prog.o'>
Task.prepare(): node <executing 0 'prog.o'>
Task.execute(): node <executing 0 'prog.o'>
cc -o prog.o -c -I. prog.c
Task.executed_with_callbacks(): node <executing 0 'prog.o'>
Task.postprocess(): node <executed 0 'prog.o'>
Task.postprocess(): removing <executed 0 'prog.o'>
Task.postprocess(): adjusted parent ref count <pending 0 'prog'>
Taskmaster: Looking for a node to evaluate
Taskmaster: Considering node <pending 0 'prog'> and its children:
Taskmaster: <executed 0 'prog.o'>
Taskmaster: Evaluating <pending 0 'prog'>
Task.make_ready_current(): node <pending 0 'prog'>
Task.prepare(): node <executing 0 'prog'>
Task.execute(): node <executing 0 'prog'>
cc -o prog prog.o
Task.executed_with_callbacks(): node <executing 0 'prog'>
Task.postprocess(): node <executed 0 'prog'>
Taskmaster: Looking for a node to evaluate
Taskmaster: No candidate anymore.
The --taskmastertrace
option
doesn't provide information about the actual
calculations involved in deciding if a file is up-to-date,
but it does show all of the dependencies
it knows about for each Node,
and the order in which those dependencies are evaluated.
This can be useful as an alternate way to determine
whether or not your SCons configuration,
or the implicit dependency scan,
has actually identified all the correct dependencies
you want it to.
Sometimes SCons doesn't build the target you want
and it's difficult to figure out why. You can use
the --debug=prepare
option
to see all the targets SCons is considering, whether
they are already up-to-date or not. The message is
printed before SCons decides whether to build the target.
When using the Duplicate
option to create variant dirs,
sometimes you may find files not getting copied to where you
expect (or not at all), or files mysteriously disappearing. These
are usually because of a misconfiguration of some kind in the
SConstruct/SConscript, but they can be tricky to debug. The
--debug=duplicate option shows each time a variant file is
unlinked and relinked from its source (or copied, depending on
settings), and also shows a message for removing "stale"
variant-dir files that no longer have a corresponding source file.
It also prints a line for each target that's removed just before
building, since that can also be mistaken for the same thing.
This appendix contains descriptions of all of the construction variables that are potentially available "out of the box" in this version of SCons. Whether or not setting a construction variable in a construction environment will actually have an effect depends on whether any of the Tools and/or Builders that use the variable have been included in the construction environment.
In this appendix, we have
appended the initial $
(dollar sign) to the beginning of each
variable name when it appears in the text,
but left off the dollar sign
in the left-hand column
where the name appears for each entry.
This construction variable automatically introduces $_LDMODULEVERSIONFLAGS
if $LDMODULEVERSION
is set. Othervise it evaluates to an empty string.
This construction variable automatically introduces $_SHLIBVERSIONFLAGS
if $SHLIBVERSION
is set. Othervise it evaluates to an empty string.
The static library archiver.
Specifies the system architecture for which
the package is being built.
The default is the system architecture
of the machine on which SCons is running.
This is used to fill in the
Architecture:
field in an Ipkg
control
file,
and as part of the name of a generated RPM file.
The command line used to generate a static library from object files.
The string displayed when an object file
is generated from an assembly-language source file.
If this is not set, then $ARCOM
(the command line) is displayed.
env = Environment(ARCOMSTR = "Archiving $TARGET")
General options passed to the static library archiver.
The assembler.
The command line used to generate an object file from an assembly-language source file.
The string displayed when an object file
is generated from an assembly-language source file.
If this is not set, then $ASCOM
(the command line) is displayed.
env = Environment(ASCOMSTR = "Assembling $TARGET")
General options passed to the assembler.
The command line used to assemble an assembly-language
source file into an object file
after first running the file through the C preprocessor.
Any options specified
in the $ASFLAGS
and $CPPFLAGS
construction variables
are included on this command line.
The string displayed when an object file
is generated from an assembly-language source file
after first running the file through the C preprocessor.
If this is not set, then $ASPPCOM
(the command line) is displayed.
env = Environment(ASPPCOMSTR = "Assembling $TARGET")
General options when an assembling an assembly-language
source file into an object file
after first running the file through the C preprocessor.
The default is to use the value of $ASFLAGS
.
The bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.
The command line used to call the bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.
The string displayed when generating a bibliography
for TeX or LaTeX.
If this is not set, then $BIBTEXCOM
(the command line) is displayed.
env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")
General options passed to the bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.
A dictionary mapping the names of the builders available through this environment to underlying Builder objects. Builders named Alias, CFile, CXXFile, DVI, Library, Object, PDF, PostScript, and Program are available by default. If you initialize this variable when an Environment is created:
env = Environment(BUILDERS = {'NewBuilder' : foo})
the default Builders will no longer be available. To use a new Builder object in addition to the default Builders, add your new Builder object like this:
env = Environment() env.Append(BUILDERS = {'NewBuilder' : foo})
or this:
env = Environment() env['BUILDERS]['NewBuilder'] = foo
The C compiler.
The command line used to compile a C source file to a (static) object
file. Any options specified in the $CFLAGS
, $CCFLAGS
and
$CPPFLAGS
construction variables are included on this command
line.
The string displayed when a C source file
is compiled to a (static) object file.
If this is not set, then $CCCOM
(the command line) is displayed.
env = Environment(CCCOMSTR = "Compiling static object $TARGET")
General options that are passed to the C and C++ compilers.
Options added to the compiler command line
to support building with precompiled headers.
The default value expands expands to the appropriate
Microsoft Visual C++ command-line options
when the $PCH
construction variable is set.
Options added to the compiler command line
to support storing debugging information in a
Microsoft Visual C++ PDB file.
The default value expands expands to appropriate
Microsoft Visual C++ command-line options
when the $PDB
construction variable is set.
The Visual C++ compiler option that SCons uses by default
to generate PDB information is /Z7
.
This works correctly with parallel (-j
) builds
because it embeds the debug information in the intermediate object files,
as opposed to sharing a single PDB file between multiple object files.
This is also the only way to get debug information
embedded into a static library.
Using the /Zi
instead may yield improved
link-time performance,
although parallel builds will no longer work.
You can generate PDB files with the /Zi
switch by overriding the default $CCPDBFLAGS
variable as follows:
env['CCPDBFLAGS'] = ['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}']
An alternative would be to use the /Zi
to put the debugging information in a separate .pdb
file for each object file by overriding
the $CCPDBFLAGS
variable as follows:
env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'
The version number of the C compiler. This may or may not be set, depending on the specific C compiler being used.
The suffix for C source files.
This is used by the internal CFile builder
when generating C files from Lex (.l) or YACC (.y) input files.
The default suffix, of course, is
.c
(lower case).
On case-insensitive systems (like Windows),
SCons also treats
.C
(upper case) files
as C files.
General options that are passed to the C compiler (C only; not C++).
A hook for modifying the file that controls the packaging build
(the .spec
for RPM,
the control
for Ipkg,
the .wxs
for MSI).
If set, the function will be called
after the SCons template for the file has been written.
XXX
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
The name of a file containing the change log text
to be included in the package.
This is included as the
%changelog
section of the RPM
.spec
file.
A function used to produce variables like $_CPPINCFLAGS
. It takes
four or five
arguments: a prefix to concatenate onto each element, a list of
elements, a suffix to concatenate onto each element, an environment
for variable interpolation, and an optional function that will be
called to transform the list before concatenation.
env['_CPPINCFLAGS'] = '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs)} $)',
The name of the directory in which
Configure context test files are written.
The default is
.sconf_temp
in the top-level directory
containing the
SConstruct
file.
The name of the Configure context log file.
The default is
config.log
in the top-level directory
containing the
SConstruct
file.
An automatically-generated construction variable
containing the C preprocessor command-line options
to define values.
The value of $_CPPDEFFLAGS
is created
by appending $CPPDEFPREFIX
and $CPPDEFSUFFIX
to the beginning and end
of each definition in $CPPDEFINES
.
A platform independent specification of C preprocessor definitions.
The definitions will be added to command lines
through the automatically-generated
$_CPPDEFFLAGS
construction variable (see above),
which is constructed according to
the type of value of $CPPDEFINES
:
If $CPPDEFINES
is a string,
the values of the
$CPPDEFPREFIX
and $CPPDEFSUFFIX
construction variables
will be added to the beginning and end.
# Will add -Dxyz to POSIX compiler command lines, # and /Dxyz to Microsoft Visual C++ command lines. env = Environment(CPPDEFINES='xyz')
If $CPPDEFINES
is a list,
the values of the
$CPPDEFPREFIX
and $CPPDEFSUFFIX
construction variables
will be appended to the beginning and end
of each element in the list.
If any element is a list or tuple,
then the first item is the name being
defined and the second item is its value:
# Will add -DB=2 -DA to POSIX compiler command lines, # and /DB=2 /DA to Microsoft Visual C++ command lines. env = Environment(CPPDEFINES=[('B', 2), 'A'])
If $CPPDEFINES
is a dictionary,
the values of the
$CPPDEFPREFIX
and $CPPDEFSUFFIX
construction variables
will be appended to the beginning and end
of each item from the dictionary.
The key of each dictionary item
is a name being defined
to the dictionary item's corresponding value;
if the value is
None
,
then the name is defined without an explicit value.
Note that the resulting flags are sorted by keyword
to ensure that the order of the options on the
command line is consistent each time
scons
is run.
# Will add -DA -DB=2 to POSIX compiler command lines, # and /DA /DB=2 to Microsoft Visual C++ command lines. env = Environment(CPPDEFINES={'B':2, 'A':None})
The prefix used to specify preprocessor definitions
on the C compiler command line.
This will be appended to the beginning of each definition
in the $CPPDEFINES
construction variable
when the $_CPPDEFFLAGS
variable is automatically generated.
The suffix used to specify preprocessor definitions
on the C compiler command line.
This will be appended to the end of each definition
in the $CPPDEFINES
construction variable
when the $_CPPDEFFLAGS
variable is automatically generated.
User-specified C preprocessor options.
These will be included in any command that uses the C preprocessor,
including not just compilation of C and C++ source files
via the $CCCOM
,
$SHCCCOM
,
$CXXCOM
and
$SHCXXCOM
command lines,
but also the $FORTRANPPCOM
,
$SHFORTRANPPCOM
,
$F77PPCOM
and
$SHF77PPCOM
command lines
used to compile a Fortran source file,
and the $ASPPCOM
command line
used to assemble an assembly language source file,
after first running each file through the C preprocessor.
Note that this variable does
not
contain
-I
(or similar) include search path options
that scons generates automatically from $CPPPATH
.
See $_CPPINCFLAGS
, below,
for the variable that expands to those options.
An automatically-generated construction variable
containing the C preprocessor command-line options
for specifying directories to be searched for include files.
The value of $_CPPINCFLAGS
is created
by appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $CPPPATH
.
The list of directories that the C preprocessor will search for include
directories. The C/C++ implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in CCFLAGS or CXXFLAGS because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in CPPPATH will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
env = Environment(CPPPATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(CPPPATH=include)
The directory list will be added to command lines
through the automatically-generated
$_CPPINCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $CPPPATH
.
Any command lines you define that need
the CPPPATH directory list should
include $_CPPINCFLAGS
:
env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")
The list of suffixes of files that will be scanned for C preprocessor implicit dependencies (#include lines). The default list is:
[".c", ".C", ".cxx", ".cpp", ".c++", ".cc", ".h", ".H", ".hxx", ".hpp", ".hh", ".F", ".fpp", ".FPP", ".m", ".mm", ".S", ".spp", ".SPP"]
The C++ compiler.
The command line used to compile a C++ source file to an object file.
Any options specified in the $CXXFLAGS
and
$CPPFLAGS
construction variables
are included on this command line.
The string displayed when a C++ source file
is compiled to a (static) object file.
If this is not set, then $CXXCOM
(the command line) is displayed.
env = Environment(CXXCOMSTR = "Compiling static object $TARGET")
The suffix for C++ source files.
This is used by the internal CXXFile builder
when generating C++ files from Lex (.ll) or YACC (.yy) input files.
The default suffix is
.cc
.
SCons also treats files with the suffixes
.cpp
,
.cxx
,
.c++
,
and
.C++
as C++ files,
and files with
.mm
suffixes as Objective C++ files.
On case-sensitive systems (Linux, UNIX, and other POSIX-alikes),
SCons also treats
.C
(upper case) files
as C++ files.
General options that are passed to the C++ compiler.
By default, this includes the value of $CCFLAGS
,
so that setting $CCFLAGS
affects both C and C++ compilation.
If you want to add C++-specific flags,
you must set or override the value of $CXXFLAGS
.
The version number of the C++ compiler. This may or may not be set, depending on the specific C++ compiler being used.
The D compiler to use.
The D compiler to use.
The D compiler to use.
The command line used to compile a D file to an object file.
Any options specified in the $DFLAGS
construction variable
is included on this command line.
The command line used to compile a D file to an object file.
Any options specified in the $DFLAGS
construction variable
is included on this command line.
The command line used to compile a D file to an object file.
Any options specified in the $DFLAGS
construction variable
is included on this command line.
List of debug tags to enable when compiling.
List of debug tags to enable when compiling.
List of debug tags to enable when compiling.
DDEBUGPREFIX.
DDEBUGPREFIX.
DDEBUGPREFIX.
DDEBUGSUFFIX.
DDEBUGSUFFIX.
DDEBUGSUFFIX.
A long description of the project being packaged. This is included in the relevant section of the file that controls the packaging build.
A language-specific long description for
the specified lang
.
This is used to populate a
%description -l
section of an RPM
.spec
file.
DFILESUFFIX.
DFILESUFFIX.
DFILESUFFIX.
DFLAGPREFIX.
DFLAGPREFIX.
DFLAGPREFIX.
General options that are passed to the D compiler.
General options that are passed to the D compiler.
General options that are passed to the D compiler.
DFLAGSUFFIX.
DFLAGSUFFIX.
DFLAGSUFFIX.
DINCPREFIX.
DINCPREFIX.
DINCPREFIX.
DLIBFLAGSUFFIX.
DLIBFLAGSUFFIX.
DLIBFLAGSUFFIX.
A function that converts a string into a Dir instance relative to the target being built.
A function that converts a string into a Dir instance relative to the target being built.
A function that converts a list of strings into a list of Dir instances relative to the target being built.
Name of the lib tool to use for D codes.
Name of the lib tool to use for D codes.
Name of the lib tool to use for D codes.
The command line to use when creating libraries.
The command line to use when creating libraries.
The command line to use when creating libraries.
DLIBLINKPREFIX.
DLIBLINKPREFIX.
DLIBLINKPREFIX.
DLIBLINKSUFFIX.
DLIBLINKSUFFIX.
DLIBLINKSUFFIX.
DLIBFLAGPREFIX.
DLIBFLAGPREFIX.
DLIBFLAGPREFIX.
DLIBFLAGSUFFIX.
DLIBFLAGSUFFIX.
DLIBFLAGSUFFIX.
DLIBLINKPREFIX.
DLIBLINKPREFIX.
DLIBLINKPREFIX.
DLIBLINKSUFFIX.
DLIBLINKSUFFIX.
DLIBLINKSUFFIX.
Name of the linker to use for linking systems including D sources.
Name of the linker to use for linking systems including D sources.
Name of the linker to use for linking systems including D sources.
The command line to use when linking systems including D sources.
The command line to use when linking systems including D sources.
The command line to use when linking systems including D sources.
DLINKFLAGPREFIX.
DLINKFLAGPREFIX.
DLINKFLAGPREFIX.
List of linker flags.
List of linker flags.
List of linker flags.
DLINKFLAGSUFFIX.
DLINKFLAGSUFFIX.
DLINKFLAGSUFFIX.
The default XSLT file for the DocbookEpub
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookHtml
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookHtmlChunked
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookHtmlhelp
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookMan
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookPdf
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookSlidesHtml
builder within the
current environment, if no other XSLT gets specified via keyword.
The default XSLT file for the DocbookSlidesPdf
builder within the
current environment, if no other XSLT gets specified via keyword.
The path to the PDF renderer fop
or xep
,
if one of them is installed (fop
gets checked first).
The full command-line for the
PDF renderer fop
or xep
.
The string displayed when a renderer like fop
or
xep
is used to create PDF output from an XML file.
Additonal command-line flags for the
PDF renderer fop
or xep
.
The path to the external executable xmllint
, if it's installed.
Note, that this is only used as last fallback for resolving
XIncludes, if no libxml2 or lxml Python binding can be imported
in the current system.
The full command-line for the external executable
xmllint
.
The string displayed when xmllint
is used to resolve
XIncludes for a given XML file.
Additonal command-line flags for the external executable
xmllint
.
The path to the external executable xsltproc
(or saxon
, xalan
), if one of them
is installed.
Note, that this is only used as last fallback for XSL transformations, if
no libxml2 or lxml Python binding can be imported in the current system.
The full command-line for the external executable
xsltproc
(or saxon
,
xalan
).
The string displayed when xsltproc
is used to transform
an XML file via a given XSLT stylesheet.
Additonal command-line flags for the external executable
xsltproc
(or saxon
,
xalan
).
Additonal parameters that are not intended for the XSLT processor executable, but
the XSL processing itself. By default, they get appended at the end of the command line
for saxon
and saxon-xslt
, respectively.
List of paths to search for import modules.
List of paths to search for import modules.
List of paths to search for import modules.
DRPATHPREFIX.
DRPATHSUFFIX.
DShLibSonameGenerator.
The list of suffixes of files that will be scanned for imported D package files. The default list is:
['.d']
DVERPREFIX.
DVERPREFIX.
DVERPREFIX.
List of version tags to enable when compiling.
List of version tags to enable when compiling.
List of version tags to enable when compiling.
DVERSUFFIX.
DVERSUFFIX.
DVERSUFFIX.
The TeX DVI file to PDF file converter.
The command line used to convert TeX DVI files into a PDF file.
The string displayed when a TeX DVI file
is converted into a PDF file.
If this is not set, then $DVIPDFCOM
(the command line) is displayed.
General options passed to the TeX DVI file to PDF file converter.
The TeX DVI file to PostScript converter.
General options passed to the TeX DVI file to PostScript converter.
A dictionary of environment variables
to use when invoking commands. When
$ENV
is used in a command all list
values will be joined using the path separator and any other non-string
values will simply be coerced to a string.
Note that, by default,
scons
does
not
propagate the environment in force when you
execute
scons
to the commands used to build target files.
This is so that builds will be guaranteed
repeatable regardless of the environment
variables set at the time
scons
is invoked.
If you want to propagate your environment variables to the commands executed to build target files, you must do so explicitly:
import os env = Environment(ENV = os.environ)
Note that you can choose only to propagate
certain environment variables.
A common example is
the system
PATH
environment variable,
so that
scons
uses the same utilities
as the invoking shell (or other process):
import os env = Environment(ENV = {'PATH' : os.environ['PATH']})
A function that will be called to escape shell special characters in command lines. The function should take one argument: the command line string to escape; and should return the escaped command line.
The Fortran 03 compiler.
You should normally set the $FORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $F03
if you need to use a specific compiler
or compiler version for Fortran 03 files.
The command line used to compile a Fortran 03 source file to an object file.
You only need to set $F03COM
if you need to use a specific
command line for Fortran 03 files.
You should normally set the $FORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 03 source file
is compiled to an object file.
If this is not set, then $F03COM
or $FORTRANCOM
(the command line) is displayed.
The list of file extensions for which the F03 dialect will be used. By default, this is ['.f03']
General user-specified options that are passed to the Fortran 03 compiler.
Note that this variable does
not
contain
-I
(or similar) include search path options
that scons generates automatically from $F03PATH
.
See
$_F03INCFLAGS
below,
for the variable that expands to those options.
You only need to set $F03FLAGS
if you need to define specific
user options for Fortran 03 files.
You should normally set the $FORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
An automatically-generated construction variable
containing the Fortran 03 compiler command-line options
for specifying directories to be searched for include files.
The value of $_F03INCFLAGS
is created
by appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $F03PATH
.
The list of directories that the Fortran 03 compiler will search for include
directories. The implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in $F03FLAGS
because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in $F03PATH
will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
You only need to set $F03PATH
if you need to define a specific
include path for Fortran 03 files.
You should normally set the $FORTRANPATH
variable,
which specifies the include path
for the default Fortran compiler
for all Fortran versions.
env = Environment(F03PATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(F03PATH=include)
The directory list will be added to command lines
through the automatically-generated
$_F03INCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $F03PATH
.
Any command lines you define that need
the F03PATH directory list should
include $_F03INCFLAGS
:
env = Environment(F03COM="my_compiler $_F03INCFLAGS -c -o $TARGET $SOURCE")
The command line used to compile a Fortran 03 source file to an object file
after first running the file through the C preprocessor.
Any options specified in the $F03FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $F03PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 03 files.
You should normally set the $FORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 03 source file
is compiled to an object file
after first running the file through the C preprocessor.
If this is not set, then $F03PPCOM
or $FORTRANPPCOM
(the command line) is displayed.
The list of file extensions for which the compilation + preprocessor pass for F03 dialect will be used. By default, this is empty
The Fortran 08 compiler.
You should normally set the $FORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $F08
if you need to use a specific compiler
or compiler version for Fortran 08 files.
The command line used to compile a Fortran 08 source file to an object file.
You only need to set $F08COM
if you need to use a specific
command line for Fortran 08 files.
You should normally set the $FORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 08 source file
is compiled to an object file.
If this is not set, then $F08COM
or $FORTRANCOM
(the command line) is displayed.
The list of file extensions for which the F08 dialect will be used. By default, this is ['.f08']
General user-specified options that are passed to the Fortran 08 compiler.
Note that this variable does
not
contain
-I
(or similar) include search path options
that scons generates automatically from $F08PATH
.
See
$_F08INCFLAGS
below,
for the variable that expands to those options.
You only need to set $F08FLAGS
if you need to define specific
user options for Fortran 08 files.
You should normally set the $FORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
An automatically-generated construction variable
containing the Fortran 08 compiler command-line options
for specifying directories to be searched for include files.
The value of $_F08INCFLAGS
is created
by appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $F08PATH
.
The list of directories that the Fortran 08 compiler will search for include
directories. The implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in $F08FLAGS
because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in $F08PATH
will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
You only need to set $F08PATH
if you need to define a specific
include path for Fortran 08 files.
You should normally set the $FORTRANPATH
variable,
which specifies the include path
for the default Fortran compiler
for all Fortran versions.
env = Environment(F08PATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(F08PATH=include)
The directory list will be added to command lines
through the automatically-generated
$_F08INCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $F08PATH
.
Any command lines you define that need
the F08PATH directory list should
include $_F08INCFLAGS
:
env = Environment(F08COM="my_compiler $_F08INCFLAGS -c -o $TARGET $SOURCE")
The command line used to compile a Fortran 08 source file to an object file
after first running the file through the C preprocessor.
Any options specified in the $F08FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $F08PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 08 files.
You should normally set the $FORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 08 source file
is compiled to an object file
after first running the file through the C preprocessor.
If this is not set, then $F08PPCOM
or $FORTRANPPCOM
(the command line) is displayed.
The list of file extensions for which the compilation + preprocessor pass for F08 dialect will be used. By default, this is empty
The Fortran 77 compiler.
You should normally set the $FORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $F77
if you need to use a specific compiler
or compiler version for Fortran 77 files.
The command line used to compile a Fortran 77 source file to an object file.
You only need to set $F77COM
if you need to use a specific
command line for Fortran 77 files.
You should normally set the $FORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 77 source file
is compiled to an object file.
If this is not set, then $F77COM
or $FORTRANCOM
(the command line) is displayed.
The list of file extensions for which the F77 dialect will be used. By default, this is ['.f77']
General user-specified options that are passed to the Fortran 77 compiler.
Note that this variable does
not
contain
-I
(or similar) include search path options
that scons generates automatically from $F77PATH
.
See
$_F77INCFLAGS
below,
for the variable that expands to those options.
You only need to set $F77FLAGS
if you need to define specific
user options for Fortran 77 files.
You should normally set the $FORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
An automatically-generated construction variable
containing the Fortran 77 compiler command-line options
for specifying directories to be searched for include files.
The value of $_F77INCFLAGS
is created
by appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $F77PATH
.
The list of directories that the Fortran 77 compiler will search for include
directories. The implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in $F77FLAGS
because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in $F77PATH
will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
You only need to set $F77PATH
if you need to define a specific
include path for Fortran 77 files.
You should normally set the $FORTRANPATH
variable,
which specifies the include path
for the default Fortran compiler
for all Fortran versions.
env = Environment(F77PATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(F77PATH=include)
The directory list will be added to command lines
through the automatically-generated
$_F77INCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $F77PATH
.
Any command lines you define that need
the F77PATH directory list should
include $_F77INCFLAGS
:
env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")
The command line used to compile a Fortran 77 source file to an object file
after first running the file through the C preprocessor.
Any options specified in the $F77FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $F77PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 77 files.
You should normally set the $FORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 77 source file
is compiled to an object file
after first running the file through the C preprocessor.
If this is not set, then $F77PPCOM
or $FORTRANPPCOM
(the command line) is displayed.
The list of file extensions for which the compilation + preprocessor pass for F77 dialect will be used. By default, this is empty
The Fortran 90 compiler.
You should normally set the $FORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $F90
if you need to use a specific compiler
or compiler version for Fortran 90 files.
The command line used to compile a Fortran 90 source file to an object file.
You only need to set $F90COM
if you need to use a specific
command line for Fortran 90 files.
You should normally set the $FORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 90 source file
is compiled to an object file.
If this is not set, then $F90COM
or $FORTRANCOM
(the command line) is displayed.
The list of file extensions for which the F90 dialect will be used. By default, this is ['.f90']
General user-specified options that are passed to the Fortran 90 compiler.
Note that this variable does
not
contain
-I
(or similar) include search path options
that scons generates automatically from $F90PATH
.
See
$_F90INCFLAGS
below,
for the variable that expands to those options.
You only need to set $F90FLAGS
if you need to define specific
user options for Fortran 90 files.
You should normally set the $FORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
An automatically-generated construction variable
containing the Fortran 90 compiler command-line options
for specifying directories to be searched for include files.
The value of $_F90INCFLAGS
is created
by appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $F90PATH
.
The list of directories that the Fortran 90 compiler will search for include
directories. The implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in $F90FLAGS
because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in $F90PATH
will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
You only need to set $F90PATH
if you need to define a specific
include path for Fortran 90 files.
You should normally set the $FORTRANPATH
variable,
which specifies the include path
for the default Fortran compiler
for all Fortran versions.
env = Environment(F90PATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(F90PATH=include)
The directory list will be added to command lines
through the automatically-generated
$_F90INCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $F90PATH
.
Any command lines you define that need
the F90PATH directory list should
include $_F90INCFLAGS
:
env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")
The command line used to compile a Fortran 90 source file to an object file
after first running the file through the C preprocessor.
Any options specified in the $F90FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $F90PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 90 files.
You should normally set the $FORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 90 source file
is compiled after first running the file through the C preprocessor.
If this is not set, then $F90PPCOM
or $FORTRANPPCOM
(the command line) is displayed.
The list of file extensions for which the compilation + preprocessor pass for F90 dialect will be used. By default, this is empty
The Fortran 95 compiler.
You should normally set the $FORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $F95
if you need to use a specific compiler
or compiler version for Fortran 95 files.
The command line used to compile a Fortran 95 source file to an object file.
You only need to set $F95COM
if you need to use a specific
command line for Fortran 95 files.
You should normally set the $FORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 95 source file
is compiled to an object file.
If this is not set, then $F95COM
or $FORTRANCOM
(the command line) is displayed.
The list of file extensions for which the F95 dialect will be used. By default, this is ['.f95']
General user-specified options that are passed to the Fortran 95 compiler.
Note that this variable does
not
contain
-I
(or similar) include search path options
that scons generates automatically from $F95PATH
.
See
$_F95INCFLAGS
below,
for the variable that expands to those options.
You only need to set $F95FLAGS
if you need to define specific
user options for Fortran 95 files.
You should normally set the $FORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
An automatically-generated construction variable
containing the Fortran 95 compiler command-line options
for specifying directories to be searched for include files.
The value of $_F95INCFLAGS
is created
by appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $F95PATH
.
The list of directories that the Fortran 95 compiler will search for include
directories. The implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in $F95FLAGS
because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in $F95PATH
will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
You only need to set $F95PATH
if you need to define a specific
include path for Fortran 95 files.
You should normally set the $FORTRANPATH
variable,
which specifies the include path
for the default Fortran compiler
for all Fortran versions.
env = Environment(F95PATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(F95PATH=include)
The directory list will be added to command lines
through the automatically-generated
$_F95INCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $F95PATH
.
Any command lines you define that need
the F95PATH directory list should
include $_F95INCFLAGS
:
env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")
The command line used to compile a Fortran 95 source file to an object file
after first running the file through the C preprocessor.
Any options specified in the $F95FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $F95PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 95 files.
You should normally set the $FORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 95 source file
is compiled to an object file
after first running the file through the C preprocessor.
If this is not set, then $F95PPCOM
or $FORTRANPPCOM
(the command line) is displayed.
The list of file extensions for which the compilation + preprocessor pass for F95 dialect will be used. By default, this is empty
A function that converts a string into a File instance relative to the target being built.
A function that converts a string into a File instance relative to the target being built.
The default Fortran compiler for all versions of Fortran.
The command line used to compile a Fortran source file to an object file.
By default, any options specified
in the $FORTRANFLAGS
,
$CPPFLAGS
,
$_CPPDEFFLAGS
,
$_FORTRANMODFLAG
, and
$_FORTRANINCFLAGS
construction variables
are included on this command line.
The string displayed when a Fortran source file
is compiled to an object file.
If this is not set, then $FORTRANCOM
(the command line) is displayed.
The list of file extensions for which the FORTRAN dialect will be used. By default, this is ['.f', '.for', '.ftn']
General user-specified options that are passed to the Fortran compiler.
Note that this variable does
not
contain
-I
(or similar) include or module search path options
that scons generates automatically from $FORTRANPATH
.
See
$_FORTRANINCFLAGS
and $_FORTRANMODFLAG
,
below,
for the variables that expand those options.
An automatically-generated construction variable
containing the Fortran compiler command-line options
for specifying directories to be searched for include
files and module files.
The value of $_FORTRANINCFLAGS
is created
by prepending/appending $INCPREFIX
and $INCSUFFIX
to the beginning and end
of each directory in $FORTRANPATH
.
Directory location where the Fortran compiler should place any module files it generates. This variable is empty, by default. Some Fortran compilers will internally append this directory in the search path for module files, as well.
The prefix used to specify a module directory on the Fortran compiler command
line.
This will be appended to the beginning of the directory
in the $FORTRANMODDIR
construction variables
when the $_FORTRANMODFLAG
variables is automatically generated.
The suffix used to specify a module directory on the Fortran compiler command
line.
This will be appended to the beginning of the directory
in the $FORTRANMODDIR
construction variables
when the $_FORTRANMODFLAG
variables is automatically generated.
An automatically-generated construction variable
containing the Fortran compiler command-line option
for specifying the directory location where the Fortran
compiler should place any module files that happen to get
generated during compilation.
The value of $_FORTRANMODFLAG
is created
by prepending/appending $FORTRANMODDIRPREFIX
and
$FORTRANMODDIRSUFFIX
to the beginning and end of the directory in $FORTRANMODDIR
.
The module file prefix used by the Fortran compiler. SCons assumes that
the Fortran compiler follows the quasi-standard naming convention for
module files of
module_name.mod
.
As a result, this variable is left empty, by default. For situations in
which the compiler does not necessarily follow the normal convention,
the user may use this variable. Its value will be appended to every
module file name as scons attempts to resolve dependencies.
The module file suffix used by the Fortran compiler. SCons assumes that
the Fortran compiler follows the quasi-standard naming convention for
module files of
module_name.mod
.
As a result, this variable is set to ".mod", by default. For situations
in which the compiler does not necessarily follow the normal convention,
the user may use this variable. Its value will be appended to every
module file name as scons attempts to resolve dependencies.
The list of directories that the Fortran compiler will search for
include files and (for some compilers) module files. The Fortran implicit
dependency scanner will search these directories for include files (but
not module files since they are autogenerated and, as such, may not
actually exist at the time the scan takes place). Don't explicitly put
include directory arguments in FORTRANFLAGS because the result will be
non-portable and the directories will not be searched by the dependency
scanner. Note: directory names in FORTRANPATH will be looked-up relative
to the SConscript directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
env = Environment(FORTRANPATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(FORTRANPATH=include)
The directory list will be added to command lines
through the automatically-generated
$_FORTRANINCFLAGS
construction variable,
which is constructed by
appending the values of the
$INCPREFIX
and $INCSUFFIX
construction variables
to the beginning and end
of each directory in $FORTRANPATH
.
Any command lines you define that need
the FORTRANPATH directory list should
include $_FORTRANINCFLAGS
:
env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")
The command line used to compile a Fortran source file to an object file
after first running the file through the C preprocessor.
By default, any options specified in the $FORTRANFLAGS
,
$CPPFLAGS
,
$_CPPDEFFLAGS
,
$_FORTRANMODFLAG
, and
$_FORTRANINCFLAGS
construction variables are included on this command line.
The string displayed when a Fortran source file
is compiled to an object file
after first running the file through the C preprocessor.
If this is not set, then $FORTRANPPCOM
(the command line) is displayed.
The list of file extensions for which the compilation + preprocessor pass for FORTRAN dialect will be used. By default, this is ['.fpp', '.FPP']
The list of suffixes of files that will be scanned for Fortran implicit dependencies (INCLUDE lines and USE statements). The default list is:
[".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP", ".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]
On Mac OS X with gcc,
a list containing the paths to search for frameworks.
Used by the compiler to find framework-style includes like
#include <Fmwk/Header.h>.
Used by the linker to find user-specified frameworks when linking (see
$FRAMEWORKS
).
For example:
env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')
will add
... -Fmyframeworkdir
to the compiler and linker command lines.
On Mac OS X with gcc, an automatically-generated construction variable
containing the linker command-line options corresponding to
$FRAMEWORKPATH
.
On Mac OS X with gcc, the prefix to be used for the FRAMEWORKPATH entries.
(see $FRAMEWORKPATH
).
The default value is
-F
.
On Mac OS X with gcc,
the prefix to be used for linking in frameworks
(see $FRAMEWORKS
).
The default value is
-framework
.
On Mac OS X with gcc, an automatically-generated construction variable containing the linker command-line options for linking with FRAMEWORKS.
On Mac OS X with gcc, a list of the framework names to be linked into a program or shared library or bundle. The default value is the empty list. For example:
env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))
On Mac OS X with gcc,
general user-supplied frameworks options to be added at
the end of a command
line building a loadable module.
(This has been largely superseded by
the $FRAMEWORKPATH
, $FRAMEWORKPATHPREFIX
,
$FRAMEWORKPREFIX
and $FRAMEWORKS
variables
described above.)
The Ghostscript program used, e.g. to convert PostScript to PDF files.
The full Ghostscript command line used for the conversion process. Its default
value is “$GS $GSFLAGS -sOutputFile=$TARGET $SOURCES
”.
The string displayed when
Ghostscript is called for the conversion process.
If this is not set (the default), then $GSCOM
(the command line) is displayed.
General options passed to the Ghostscript program,
when converting PostScript to PDF files for example. Its default value
is “-dNOPAUSE -dBATCH -sDEVICE=pdfwrite
”
The name of the host hardware architecture used to create the Environment. If a platform is specified when creating the Environment, then that Platform's logic will handle setting this value. This value is immutable, and should not be changed by the user after the Environment is initialized. Currently only set for Win32.
Sets the host architecture for Visual Studio compiler. If not set, default to the detected host architecture: note that this may depend on the python you are using. This variable must be passed as an argument to the Environment() constructor; setting it later has no effect.
Valid values are the same as for $TARGET_ARCH
.
This is currently only used on Windows, but in the future it will be used on other OSes as well.
The name of the host operating system used to create the Environment. If a platform is specified when creating the Environment, then that Platform's logic will handle setting this value. This value is immutable, and should not be changed by the user after the Environment is initialized. Currently only set for Win32.
The list of suffixes of files that will be scanned for IDL implicit dependencies (#include or import lines). The default list is:
[".idl", ".IDL"]
Used to override $SHLIBNOVERSIONSYMLINKS
/$LDMODULENOVERSIONSYMLINKS
when
creating versioned import library for a shared library/loadable module. If not defined,
then $SHLIBNOVERSIONSYMLINKS
/$LDMODULENOVERSIONSYMLINKS
is used to determine
whether to disable symlink generation or not.
The prefix used for import library names. For example, cygwin uses import
libraries (libfoo.dll.a
) in pair with dynamic libraries
(cygfoo.dll
). The cyglink
linker sets
$IMPLIBPREFIX
to 'lib'
and $SHLIBPREFIX
to 'cyg'
.
The suffix used for import library names. For example, cygwin uses import
libraries (libfoo.dll.a
) in pair with dynamic libraries
(cygfoo.dll
). The cyglink
linker sets
$IMPLIBSUFFIX
to '.dll.a'
and $SHLIBSUFFIX
to '.dll'
.
Used to override $SHLIBVERSION
/$LDMODULEVERSION
when
generating versioned import library for a shared library/loadable module. If
undefined, the $SHLIBVERSION
/$LDMODULEVERSION
is used to
determine the version of versioned import library.
Controls whether or not SCons will add implicit dependencies for the commands executed to build targets.
By default, SCons will add
to each target
an implicit dependency on the command
represented by the first argument on any
command line it executes.
The specific file for the dependency is
found by searching the
PATH
variable in the
ENV
environment used to execute the command.
If the construction variable
$IMPLICIT_COMMAND_DEPENDENCIES
is set to a false value
(None
,
False
,
0
,
etc.),
then the implicit dependency will
not be added to the targets
built with that construction environment.
env = Environment(IMPLICIT_COMMAND_DEPENDENCIES = 0)
The prefix used to specify an include directory on the C compiler command
line.
This will be appended to the beginning of each directory
in the $CPPPATH
and $FORTRANPATH
construction variables
when the $_CPPINCFLAGS
and $_FORTRANINCFLAGS
variables are automatically generated.
The suffix used to specify an include directory on the C compiler command
line.
This will be appended to the end of each directory
in the $CPPPATH
and $FORTRANPATH
construction variables
when the $_CPPINCFLAGS
and $_FORTRANINCFLAGS
variables are automatically generated.
A function to be called to install a file into a destination file name. The default function copies the file into the destination (and sets the destination file's mode and permission bits to match the source file's). The function takes the following arguments:
def install(dest, source, env):
dest
is the path name of the destination file.
source
is the path name of the source file.
env
is the construction environment
(a dictionary of construction values)
in force for this file installation.
The string displayed when a file is installed into a destination file name. The default is:
Install file: "$SOURCE" as "$TARGET"
Set by the "intelc" Tool to the major version number of the Intel C compiler selected for use.
The Java archive tool.
The Java archive tool.
The directory to which the Java archive tool should change
(using the
-C
option).
The directory to which the Java archive tool should change
(using the
-C
option).
The command line used to call the Java archive tool.
The command line used to call the Java archive tool.
The string displayed when the Java archive tool
is called
If this is not set, then $JARCOM
(the command line) is displayed.
env = Environment(JARCOMSTR = "JARchiving $SOURCES into $TARGET")
The string displayed when the Java archive tool
is called
If this is not set, then $JARCOM
(the command line) is displayed.
env = Environment(JARCOMSTR = "JARchiving $SOURCES into $TARGET")
General options passed to the Java archive tool.
By default this is set to
cf
to create the necessary
jar
file.
General options passed to the Java archive tool.
By default this is set to
cf
to create the necessary
jar
file.
The suffix for Java archives:
.jar
by default.
The suffix for Java archives:
.jar
by default.
Specifies the list of directories that
will be added to the
javac command line
via the -bootclasspath
option.
The individual directory names will be
separated by the operating system's path separate character
(:
on UNIX/Linux/POSIX,
;
on Windows).
The Java compiler.
The command line used to compile a directory tree containing
Java source files to
corresponding Java class files.
Any options specified in the $JAVACFLAGS
construction variable
are included on this command line.
The string displayed when compiling
a directory tree of Java source files to
corresponding Java class files.
If this is not set, then $JAVACCOM
(the command line) is displayed.
env = Environment(JAVACCOMSTR = "Compiling class files $TARGETS from $SOURCES")
General options that are passed to the Java compiler.
The directory in which Java class files may be found.
This is stripped from the beginning of any Java .class
file names supplied to the
JavaH
builder.
Specifies the list of directories that
will be searched for Java
.class
file.
The directories in this list will be added to the
javac and javah command lines
via the -classpath
option.
The individual directory names will be
separated by the operating system's path separate character
(:
on UNIX/Linux/POSIX,
;
on Windows).
Note that this currently just adds the specified
directory via the -classpath
option.
SCons does not currently search the
$JAVACLASSPATH
directories for dependency
.class
files.
The suffix for Java class files;
.class
by default.
The Java generator for C header and stub files.
The command line used to generate C header and stub files
from Java classes.
Any options specified in the $JAVAHFLAGS
construction variable
are included on this command line.
The string displayed when C header and stub files
are generated from Java classes.
If this is not set, then $JAVAHCOM
(the command line) is displayed.
env = Environment(JAVAHCOMSTR = "Generating header/stub file(s) $TARGETS from $SOURCES")
General options passed to the C header and stub file generator for Java classes.
Specifies the list of directories that
will be searched for input
.java
file.
The directories in this list will be added to the
javac command line
via the -sourcepath
option.
The individual directory names will be
separated by the operating system's path separate character
(:
on UNIX/Linux/POSIX,
;
on Windows).
Note that this currently just adds the specified
directory via the -sourcepath
option.
SCons does not currently search the
$JAVASOURCEPATH
directories for dependency
.java
files.
The suffix for Java files;
.java
by default.
Specifies the Java version being used by the Java
builder.
This is not currently used to select one
version of the Java compiler vs. another.
Instead, you should set this to specify the version of Java
supported by your javac compiler.
The default is 1.4
.
This is sometimes necessary because
Java 1.5 changed the file names that are created
for nested anonymous inner classes,
which can cause a mismatch with the files
that SCons expects will be generated by the javac compiler.
Setting $JAVAVERSION
to 1.5
(or 1.6
, as appropriate)
can make SCons realize that a Java 1.5 or 1.6
build is actually up to date.
The LaTeX structured formatter and typesetter.
The command line used to call the LaTeX structured formatter and typesetter.
The string displayed when calling
the LaTeX structured formatter and typesetter.
If this is not set, then $LATEXCOM
(the command line) is displayed.
env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")
General options passed to the LaTeX structured formatter and typesetter.
The maximum number of times that LaTeX
will be re-run if the
.log
generated by the $LATEXCOM
command
indicates that there are undefined references.
The default is to try to resolve undefined references
by re-running LaTeX up to three times.
The list of suffixes of files that will be scanned
for LaTeX implicit dependencies
(\include
or \import
files).
The default list is:
[".tex", ".ltx", ".latex"]
The linker for building loadable modules.
By default, this is the same as $SHLINK
.
The command line for building loadable modules.
On Mac OS X, this uses the $LDMODULE
,
$LDMODULEFLAGS
and
$FRAMEWORKSFLAGS
variables.
On other systems, this is the same as $SHLINK
.
The string displayed when building loadable modules.
If this is not set, then $LDMODULECOM
(the command line) is displayed.
General user options passed to the linker for building loadable modules.
Instructs the LoadableModule
builder to not automatically create symlinks
for versioned modules. Defaults to $SHLIBNOVERSIONSYMLINKS
The prefix used for loadable module file names.
On Mac OS X, this is null;
on other systems, this is
the same as $SHLIBPREFIX
.
A macro that automatically generates loadable module's SONAME based on $TARGET,
$LDMODULEVERSION and $LDMODULESUFFIX. Used by LoadableModule
builder
when the linker tool supports SONAME (e.g. gnulink
).
The suffix used for loadable module file names. On Mac OS X, this is null; on other systems, this is the same as $SHLIBSUFFIX.
When this construction variable is defined, a versioned loadable module
is created by LoadableModule
builder. This activates the
$_LDMODULEVERSIONFLAGS
and thus modifies the $LDMODULECOM
as
required, adds the version number to the library name, and creates the symlinks
that are needed. $LDMODULEVERSION
versions should exist in the same
format as $SHLIBVERSION
.
Extra flags added to $LDMODULECOM
when building versioned
LoadableModule
. These flags are only used when $LDMODULEVERSION
is
set.
This macro automatically introduces extra flags to $LDMODULECOM
when
building versioned LoadableModule
(that is when
$LDMODULEVERSION
is set). _LDMODULEVERSIONFLAGS
usually adds $SHLIBVERSIONFLAGS
and some extra dynamically generated
options (such as -Wl,-soname=$_LDMODULESONAME
). It is unused
by plain (unversioned) loadable modules.
The lexical analyzer generator.
The command line used to call the lexical analyzer generator to generate a source file.
The string displayed when generating a source file
using the lexical analyzer generator.
If this is not set, then $LEXCOM
(the command line) is displayed.
env = Environment(LEXCOMSTR = "Lex'ing $TARGET from $SOURCES")
General options passed to the lexical analyzer generator.
An automatically-generated construction variable
containing the linker command-line options
for specifying directories to be searched for library.
The value of $_LIBDIRFLAGS
is created
by appending $LIBDIRPREFIX
and $LIBDIRSUFFIX
to the beginning and end
of each directory in $LIBPATH
.
The prefix used to specify a library directory on the linker command line.
This will be appended to the beginning of each directory
in the $LIBPATH
construction variable
when the $_LIBDIRFLAGS
variable is automatically generated.
The suffix used to specify a library directory on the linker command line.
This will be appended to the end of each directory
in the $LIBPATH
construction variable
when the $_LIBDIRFLAGS
variable is automatically generated.
TODO
An automatically-generated construction variable
containing the linker command-line options
for specifying libraries to be linked with the resulting target.
The value of $_LIBFLAGS
is created
by appending $LIBLINKPREFIX
and $LIBLINKSUFFIX
to the beginning and end
of each filename in $LIBS
.
The prefix used to specify a library to link on the linker command line.
This will be appended to the beginning of each library
in the $LIBS
construction variable
when the $_LIBFLAGS
variable is automatically generated.
The suffix used to specify a library to link on the linker command line.
This will be appended to the end of each library
in the $LIBS
construction variable
when the $_LIBFLAGS
variable is automatically generated.
The list of directories that will be searched for libraries.
The implicit dependency scanner will search these
directories for include files. Don't explicitly put include directory
arguments in $LINKFLAGS
or $SHLINKFLAGS
because the result will be non-portable
and the directories will not be searched by the dependency scanner. Note:
directory names in LIBPATH will be looked-up relative to the SConscript
directory when they are used in a command. To force
scons
to look-up a directory relative to the root of the source tree use #:
env = Environment(LIBPATH='#/libs')
The directory look-up can also be forced using the
Dir
()
function:
libs = Dir('libs') env = Environment(LIBPATH=libs)
The directory list will be added to command lines
through the automatically-generated
$_LIBDIRFLAGS
construction variable,
which is constructed by
appending the values of the
$LIBDIRPREFIX
and $LIBDIRSUFFIX
construction variables
to the beginning and end
of each directory in $LIBPATH
.
Any command lines you define that need
the LIBPATH directory list should
include $_LIBDIRFLAGS
:
env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")
The prefix used for (static) library file names. A default value is set for each platform (posix, win32, os2, etc.), but the value is overridden by individual tools (ar, mslib, sgiar, sunar, tlib, etc.) to reflect the names of the libraries they create.
A list of all legal prefixes for library file names.
When searching for library dependencies,
SCons will look for files with these prefixes,
the base library name,
and suffixes in the $LIBSUFFIXES
list.
A list of one or more libraries that will be linked with any executable programs created by this environment.
The library list will be added to command lines
through the automatically-generated
$_LIBFLAGS
construction variable,
which is constructed by
appending the values of the
$LIBLINKPREFIX
and $LIBLINKSUFFIX
construction variables
to the beginning and end
of each filename in $LIBS
.
Any command lines you define that need
the LIBS library list should
include $_LIBFLAGS
:
env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")
If you add a
File
object to the
$LIBS
list, the name of that file will be added to
$_LIBFLAGS
,
and thus the link line, as is, without
$LIBLINKPREFIX
or
$LIBLINKSUFFIX
.
For example:
env.Append(LIBS=File('/tmp/mylib.so'))
In all cases, scons will add dependencies from the executable program to all the libraries in this list.
The suffix used for (static) library file names. A default value is set for each platform (posix, win32, os2, etc.), but the value is overridden by individual tools (ar, mslib, sgiar, sunar, tlib, etc.) to reflect the names of the libraries they create.
A list of all legal suffixes for library file names.
When searching for library dependencies,
SCons will look for files with prefixes, in the $LIBPREFIXES
list,
the base library name,
and these suffixes.
The abbreviated name of the license under which this project is released (gpl, lpgl, bsd etc.). See http://www.opensource.org/licenses/alphabetical for a list of license names.
The separator used by the Substfile
and Textfile
builders.
This value is used between sources when constructing the target.
It defaults to the current system line separator.
The $LINGUAS_FILE
defines file(s) containing list of additional linguas
to be processed by POInit
, POUpdate
or MOFiles
builders. It also affects Translate
builder. If the variable contains
a string, it defines name of the list file. The $LINGUAS_FILE
may be a
list of file names as well. If $LINGUAS_FILE
is set to
True
(or non-zero numeric value), the list will be read from
default file named
LINGUAS
.
The linker.
The command line used to link object files into an executable.
The string displayed when object files
are linked into an executable.
If this is not set, then $LINKCOM
(the command line) is displayed.
env = Environment(LINKCOMSTR = "Linking $TARGET")
General user options passed to the linker.
Note that this variable should
not
contain
-l
(or similar) options for linking with the libraries listed in $LIBS
,
nor
-L
(or similar) library search path options
that scons generates automatically from $LIBPATH
.
See
$_LIBFLAGS
above,
for the variable that expands to library-link options,
and
$_LIBDIRFLAGS
above,
for the variable that expands to library search path options.
The M4 macro preprocessor.
The command line used to pass files through the M4 macro preprocessor.
The string displayed when
a file is passed through the M4 macro preprocessor.
If this is not set, then $M4COM
(the command line) is displayed.
General options passed to the M4 macro preprocessor.
The makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.
The command line used to call the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.
The string displayed when calling the makeindex generator for the
TeX formatter and typesetter
and the LaTeX structured formatter and typesetter.
If this is not set, then $MAKEINDEXCOM
(the command line) is displayed.
General options passed to the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.
The maximum number of characters allowed on an external command line. On Win32 systems, link lines longer than this many characters are linked via a temporary file name.
The Microsoft IDL compiler.
The command line used to pass files to the Microsoft IDL compiler.
The string displayed when
the Microsoft IDL copmiler is called.
If this is not set, then $MIDLCOM
(the command line) is displayed.
General options passed to the Microsoft IDL compiler.
Suffix used for MO
files (default: '.mo'
).
See msgfmt
tool and MOFiles
builder.
Absolute path to msgfmt(1) binary, found by
Detect()
.
See msgfmt
tool and MOFiles
builder.
Complete command line to run msgfmt(1) program.
See msgfmt
tool and MOFiles
builder.
String to display when msgfmt(1) is invoked
(default: ''
, which means ``print $MSGFMTCOM
'').
See msgfmt
tool and MOFiles
builder.
Additional flags to msgfmt(1).
See msgfmt
tool and MOFiles
builder.
Path to msginit(1) program (found via
Detect()
).
See msginit
tool and POInit
builder.
Complete command line to run msginit(1) program.
See msginit
tool and POInit
builder.
String to display when msginit(1) is invoked
(default: ''
, which means ``print $MSGINITCOM
'').
See msginit
tool and POInit
builder.
List of additional flags to msginit(1) (default:
[]
).
See msginit
tool and POInit
builder.
Internal ``macro''. Computes locale (language) name based on target filename
(default: '${TARGET.filebase}'
).
Absolute path to msgmerge(1) binary as found by
Detect()
.
See msgmerge
tool and POUpdate
builder.
Complete command line to run msgmerge(1) command.
See msgmerge
tool and POUpdate
builder.
String to be displayed when msgmerge(1) is invoked
(default: ''
, which means ``print $MSGMERGECOM
'').
See msgmerge
tool and POUpdate
builder.
Additional flags to msgmerge(1) command.
See msgmerge
tool and POUpdate
builder.
The directory containing the Microsoft SDK (either Platform SDK or Windows SDK) to be used for compilation.
The version string of the Microsoft SDK
(either Platform SDK or Windows SDK)
to be used for compilation.
Supported versions include
6.1
,
6.0A
,
6.0
,
2003R2
and
2003R1
.
When set to any true value,
specifies that SCons should batch
compilation of object files
when calling the Microsoft Visual C/C++ compiler.
All compilations of source files from the same source directory
that generate target files in a same output directory
and were configured in SCons using the same construction environment
will be built in a single call to the compiler.
Only source files that have changed since their
object files were built will be passed to each compiler invocation
(via the $CHANGED_SOURCES
construction variable).
Any compilations where the object (target) file base name
(minus the .obj
)
does not match the source file base name
will be compiled separately.
Use a batch script to set up Microsoft Visual Studio compiler
$MSVC_USE_SCRIPT
overrides $MSVC_VERSION
and $TARGET_ARCH
.
If set to the name of a Visual Studio .bat file (e.g. vcvars.bat),
SCons will run that bat file and extract the relevant variables from
the result (typically %INCLUDE%, %LIB%, and %PATH%). Setting
MSVC_USE_SCRIPT to None bypasses the Visual Studio autodetection
entirely; use this if you are running SCons in a Visual Studio cmd
window and importing the shell's environment variables.
Build libraries for a Universal Windows Platform (UWP) Application.
If $MSVC_UWP_APP
is set, the Visual Studio environment will be set up to point
to the Windows Store compatible libraries and Visual Studio runtimes. In doing so,
any libraries that are built will be able to be used in a UWP App and published
to the Windows Store.
This flag will only have an effect with Visual Studio 2015+.
This variable must be passed as an argument to the Environment()
constructor; setting it later has no effect.
Valid values are '1' or '0'
Sets the preferred version of Microsoft Visual C/C++ to use.
If $MSVC_VERSION
is not set, SCons will (by default) select the
latest version of Visual C/C++ installed on your system. If the
specified version isn't installed, tool initialization will fail.
This variable must be passed as an argument to the Environment()
constructor; setting it later has no effect.
Valid values for Windows are
14.0
,
14.0Exp
,
12.0
,
12.0Exp
,
11.0
,
11.0Exp
,
10.0
,
10.0Exp
,
9.0
,
9.0Exp
,
8.0
,
8.0Exp
,
7.1
,
7.0
,
and 6.0
.
Versions ending in Exp
refer to "Express" or
"Express for Desktop" editions.
When the Microsoft Visual Studio tools are initialized, they set up this dictionary with the following keys:
the version of MSVS being used (can be set via
$MSVS_VERSION
)
the available versions of MSVS installed
installed directory of Visual C++
installed directory of Visual Studio
installed directory of the .NET framework
list of installed versions of the .NET framework, sorted latest to oldest.
latest installed version of the .NET framework
installed location of the .NET SDK.
installed location of the Platform SDK.
dictionary of installed Platform SDK modules, where the dictionary keys are keywords for the various modules, and the values are 2-tuples where the first is the release date, and the second is the version number.
If a value isn't set, it wasn't available in the registry.
Sets the architecture for which the generated project(s) should build.
The default value is x86
. amd64
is
also supported by SCons for some Visual Studio versions. Trying to set
$MSVS_ARCH
to an architecture that's not supported for a given Visual
Studio version will generate an error.
The string placed in a generated
Microsoft Visual Studio project file as the value of the
ProjectGUID
attribute. There is no default value. If not
defined, a new GUID is generated.
The path name placed in a generated
Microsoft Visual Studio project file as the value of the
SccAuxPath
attribute if the
MSVS_SCC_PROVIDER
construction variable is also set. There is
no default value.
The root path of projects in
your SCC workspace, i.e the path under which all project and solution files
will be generated. It is used as a reference path from which the relative
paths of the generated Microsoft Visual Studio project and solution files are
computed. The relative project file path is placed as the value of the
SccLocalPath
attribute of the project file and as the
values of the
SccProjectFilePathRelativizedFromConnection[i]
(where [i]
ranges from 0 to the number of projects in the solution) attributes of the
GlobalSection(SourceCodeControl)
section of the Microsoft
Visual Studio solution file. Similarly the relative solution file path is
placed as the values of the SccLocalPath[i]
(where [i]
ranges from 0 to the number of projects in the solution) attributes of the
GlobalSection(SourceCodeControl)
section of the Microsoft
Visual Studio solution file. This is used only if the
MSVS_SCC_PROVIDER
construction variable is also set. The
default value is the current working directory.
The project name placed in
a generated Microsoft Visual Studio project file as the value of the
SccProjectName
attribute if the
MSVS_SCC_PROVIDER
construction variable is also set. In this
case the string is also placed in the SccProjectName0
attribute of the GlobalSection(SourceCodeControl)
section
of the Microsoft Visual Studio solution file. There is no default value.
The
string placed in a generated Microsoft Visual Studio project file as the value
of the SccProvider
attribute. The string is also placed in
the SccProvider0
attribute of the
GlobalSection(SourceCodeControl)
section of the Microsoft
Visual Studio solution file. There is no default value.
Sets the preferred version of Microsoft Visual Studio to use.
If $MSVS_VERSION
is not
set, SCons will (by default) select the latest version of Visual Studio
installed on your system. So, if you have version 6 and version 7 (MSVS .NET)
installed, it will prefer version 7. You can override this by specifying the
MSVS_VERSION
variable in the Environment initialization,
setting it to the appropriate version ('6.0' or '7.0', for example). If the
specified version isn't installed, tool initialization will fail.
This is obsolete: use $MSVC_VERSION
instead. If $MSVS_VERSION
is
set and $MSVC_VERSION
is not, $MSVC_VERSION
will be set automatically
to $MSVS_VERSION
. If both are set to different values, scons will raise an
error.
The build command line placed in a generated Microsoft Visual Studio project file. The default is to have Visual Studio invoke SCons with any specified build targets.
The clean command line placed in a generated Microsoft Visual Studio project file. The default is to have Visual Studio invoke SCons with the -c option to remove any specified targets.
The encoding string placed in a
generated Microsoft Visual Studio project file. The default is encoding
Windows-1252
.
The action used to generate Microsoft Visual Studio project files.
The suffix used for Microsoft Visual
Studio project (DSP) files. The default value is .vcproj
when using Visual Studio version 7.x (.NET) or later version, and
.dsp
when using earlier versions of Visual Studio.
The rebuild command line placed in a generated Microsoft Visual Studio project file. The default is to have Visual Studio invoke SCons with any specified rebuild targets.
The SCons used in generated Microsoft Visual Studio project files. The default is the version of SCons being used to generate the project file.
The default SCons command used in generated Microsoft Visual Studio project files.
The sconscript
file (that is, SConstruct
or SConscript
file) that will be invoked by
Visual Studio project files (through the $MSVSSCONSCOM
variable). The
default is the same sconscript file that contains the call to MSVSProject
to build the project file.
The SCons flags used in generated Microsoft Visual Studio project files.
The action used to generate Microsoft Visual Studio solution files.
The suffix used for Microsoft
Visual Studio solution (DSW) files. The default value is
.sln
when using Visual Studio version 7.x (.NET), and
.dsw
when using earlier versions of Visual Studio.
The program used on Windows systems to embed manifests into DLLs and EXEs.
See also $WINDOWS_EMBED_MANIFEST
.
The Windows command line used to embed manifests into executables.
See also $MTSHLIBCOM
.
Flags passed to the $MT
manifest embedding program (Windows only).
The Windows command line used to embed manifests into shared libraries (DLLs).
See also $MTEXECOM
.
The version number of the MetroWerks CodeWarrior C compiler to be used.
A list of installed versions of the MetroWerks CodeWarrior C compiler on this system.
Specfies the name of the project to package.
When set to non-zero,
suppresses creation of a corresponding Windows static import lib by the
SharedLibrary
builder when used with
MinGW, Microsoft Visual Studio or Metrowerks.
This also suppresses creation
of an export (.exp) file
when using Microsoft Visual Studio.
The prefix used for (static) object file names.
The suffix used for (static) object file names.
Specifies the directory where all files in resulting archive will be placed if applicable. The default value is "$NAME-$VERSION".
Selects the package type to build. Currently these are available:
* msi - Microsoft Installer * rpm - Redhat Package Manger * ipkg - Itsy Package Management System * tarbz2 - compressed tar * targz - compressed tar * zip - zip file * src_tarbz2 - compressed tar source * src_targz - compressed tar source * src_zip - zip file source
This may be overridden with the "package_type" command line option.
The version of the package (not the underlying project). This is currently only used by the rpm packager and should reflect changes in the packaging, not the underlying project code itself.
The Microsoft Visual C++ precompiled header that will be used when compiling object files. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler command line to cause it to use the precompiled header, and will also set up the dependencies for the PCH file. Example:
env['PCH'] = 'StdAfx.pch'
The command line used by the
PCH
builder to generated a precompiled header.
The string displayed when generating a precompiled header.
If this is not set, then $PCHCOM
(the command line) is displayed.
A construction variable that, when expanded,
adds the /yD
flag to the command line
only if the $PDB
construction variable is set.
This variable specifies how much of a source file is precompiled. This variable is ignored by tools other than Microsoft Visual C++, or when the PCH variable is not being used. When this variable is define it must be a string that is the name of the header that is included at the end of the precompiled portion of the source files, or the empty string if the "#pragma hrdstop" construct is being used:
env['PCHSTOP'] = 'StdAfx.h'
The Microsoft Visual C++ PDB file that will store debugging information for object files, shared libraries, and programs. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler and linker command line to cause them to generate external debugging information, and will also set up the dependencies for the PDB file. Example:
env['PDB'] = 'hello.pdb'
The Visual C++ compiler switch that SCons uses by default
to generate PDB information is /Z7
.
This works correctly with parallel (-j
) builds
because it embeds the debug information in the intermediate object files,
as opposed to sharing a single PDB file between multiple object files.
This is also the only way to get debug information
embedded into a static library.
Using the /Zi
instead may yield improved
link-time performance,
although parallel builds will no longer work.
You can generate PDB files with the /Zi
switch by overriding the default $CCPDBFLAGS
variable;
see the entry for that variable for specific examples.
A deprecated synonym for $DVIPDFCOM
.
The pdflatex utility.
The command line used to call the pdflatex utility.
The string displayed when calling the pdflatex utility.
If this is not set, then $PDFLATEXCOM
(the command line) is displayed.
env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")
General options passed to the pdflatex utility.
The prefix used for PDF file names.
The suffix used for PDF file names.
The pdftex utility.
The command line used to call the pdftex utility.
The string displayed when calling the pdftex utility.
If this is not set, then $PDFTEXCOM
(the command line) is displayed.
env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")
General options passed to the pdftex utility.
On Solaris systems,
the package-checking program that will
be used (along with $PKGINFO
)
to look for installed versions of
the Sun PRO C++ compiler.
The default is
/usr/sbin/pgkchk
.
On Solaris systems,
the package information program that will
be used (along with $PKGCHK
)
to look for installed versions of
the Sun PRO C++ compiler.
The default is
pkginfo
.
The name of the platform used to create the Environment. If no platform is
specified when the Environment is created,
scons
autodetects the platform.
env = Environment(tools = []) if env['PLATFORM'] == 'cygwin': Tool('mingw')(env) else: Tool('msvc')(env)
The $POAUTOINIT
variable, if set to True
(on non-zero
numeric value), let the msginit
tool to automatically initialize
missing PO
files with
msginit(1). This applies to both,
POInit
and POUpdate
builders (and others that use any of
them).
Common alias for all PO
files created with POInit
builder (default: 'po-create'
).
See msginit
tool and POInit
builder.
Suffix used for PO
files (default: '.po'
)
See msginit
tool and POInit
builder.
The $POTDOMAIN
defines default domain, used to generate
POT
filename as
when
no $POTDOMAIN
.potPOT
file name is provided by the user. This applies to
POTUpdate
, POInit
and POUpdate
builders (and
builders, that use them, e.g. Translate
). Normally (if $POTDOMAIN
is
not defined), the builders use messages.pot
as default
POT
file name.
Suffix used for PO Template files (default: '.pot'
).
See xgettext
tool and POTUpdate
builder.
Name of the common phony target for all PO Templates created with
POUpdate
(default: 'pot-update'
).
See xgettext
tool and POTUpdate
builder.
Common alias for all PO
files being defined with
POUpdate
builder (default: 'po-update'
).
See msgmerge
tool and POUpdate
builder.
A Python function used to print the command lines as they are executed
(assuming command printing is not disabled by the
-q
or
-s
options or their equivalents).
The function should take four arguments:
s
,
the command being executed (a string),
target
,
the target being built (file node, list, or string name(s)),
source
,
the source(s) used (file node, list, or string name(s)), and
env
,
the environment being used.
The function must do the printing itself. The default implementation, used if this variable is not set or is None, is:
def print_cmd_line(s, target, source, env): sys.stdout.write(s + "\n")
Here's an example of a more interesting function:
def print_cmd_line(s, target, source, env): sys.stdout.write("Building %s -> %s...\n" % (' and '.join([str(x) for x in source]), ' and '.join([str(x) for x in target]))) env=Environment(PRINT_CMD_LINE_FUNC=print_cmd_line) env.Program('foo', 'foo.c')
This just prints "Building targetname
from sourcename
..." instead
of the actual commands.
Such a function could also log the actual commands to a log file,
for example.
TODO
The prefix used for executable file names.
The suffix used for executable file names.
The command line used to convert TeX DVI files into a PostScript file.
The string displayed when a TeX DVI file
is converted into a PostScript file.
If this is not set, then $PSCOM
(the command line) is displayed.
The prefix used for PostScript file names.
The prefix used for PostScript file names.
Turn off scanning for mocable files. Use the Moc Builder to explicitly specify files to run moc on.
The path where the qt binaries are installed.
The default value is '$QTDIR
/bin'.
The path where the qt header files are installed.
The default value is '$QTDIR
/include'.
Note: If you set this variable to None,
the tool won't change the $CPPPATH
construction variable.
Prints lots of debugging information while scanning for moc files.
Default value is 'qt'. You may want to set this to 'qt-mt'. Note: If you set
this variable to None, the tool won't change the $LIBS
variable.
The path where the qt libraries are installed.
The default value is '$QTDIR
/lib'.
Note: If you set this variable to None,
the tool won't change the $LIBPATH
construction variable.
Default value is '$QT_BINPATH
/moc'.
Default value is ''. Prefix for moc output files, when source is a cxx file.
Default value is '.moc'. Suffix for moc output files, when source is a cxx file.
Command to generate a moc file from a cpp file.
The string displayed when generating a moc file from a cpp file.
If this is not set, then $QT_MOCFROMCXXCOM
(the command line) is displayed.
Default value is '-i'. These flags are passed to moc, when moccing a C++ file.
Command to generate a moc file from a header.
The string displayed when generating a moc file from a cpp file.
If this is not set, then $QT_MOCFROMHCOM
(the command line) is displayed.
Default value is ''. These flags are passed to moc, when moccing a header file.
Default value is 'moc_'. Prefix for moc output files, when source is a header.
Default value is '$CXXFILESUFFIX
'. Suffix for moc output files, when source is
a header.
Default value is '$QT_BINPATH
/uic'.
Command to generate header files from .ui files.
The string displayed when generating header files from .ui files.
If this is not set, then $QT_UICCOM
(the command line) is displayed.
Default value is ''. These flags are passed to uic, when creating a a h file from a .ui file.
Default value is ''. Prefix for uic generated header files.
Default value is '.h'. Suffix for uic generated header files.
Default value is ''. These flags are passed to uic, when creating a cxx file from a .ui file.
Default value is 'uic_'. Prefix for uic generated implementation files.
Default value is '$CXXFILESUFFIX
'. Suffix for uic generated implementation
files.
Default value is '.ui'. Suffix of designer input files.
The qt tool tries to take this from os.environ.
It also initializes all QT_*
construction variables listed below.
(Note that all paths are constructed
with python's os.path.join() method,
but are listed here with the '/' separator
for easier reading.)
In addition, the construction environment
variables $CPPPATH
,
$LIBPATH
and
$LIBS
may be modified
and the variables
$PROGEMITTER
, $SHLIBEMITTER
and $LIBEMITTER
are modified. Because the build-performance is affected when using this tool,
you have to explicitly specify it at Environment creation:
Environment(tools=['default','qt'])
The qt tool supports the following operations:
Automatic moc file generation from header files.
You do not have to specify moc files explicitly, the tool does it for you.
However, there are a few preconditions to do so: Your header file must have
the same filebase as your implementation file and must stay in the same
directory. It must have one of the suffixes .h, .hpp, .H, .hxx, .hh. You
can turn off automatic moc file generation by setting QT_AUTOSCAN to 0.
See also the corresponding
Moc
()
builder method.
Automatic moc file generation from cxx files.
As stated in the qt documentation, include the moc file at the end of
the cxx file. Note that you have to include the file, which is generated
by the transformation ${QT_MOCCXXPREFIX}<basename>${QT_MOCCXXSUFFIX}, by default
<basename>.moc. A warning is generated after building the moc file, if you
do not include the correct file. If you are using VariantDir, you may
need to specify duplicate=1. You can turn off automatic moc file generation
by setting QT_AUTOSCAN to 0. See also the corresponding
Moc
builder method.
Automatic handling of .ui files.
The implementation files generated from .ui files are handled much the same
as yacc or lex files. Each .ui file given as a source of Program, Library or
SharedLibrary will generate three files, the declaration file, the
implementation file and a moc file. Because there are also generated headers,
you may need to specify duplicate=1 in calls to VariantDir.
See also the corresponding
Uic
builder method.
The archive indexer.
The command line used to index a static library archive.
The string displayed when a static library archive is indexed.
If this is not set, then $RANLIBCOM
(the command line) is displayed.
env = Environment(RANLIBCOMSTR = "Indexing $TARGET")
General options passed to the archive indexer.
The resource compiler used to build a Microsoft Visual C++ resource file.
The command line used to build a Microsoft Visual C++ resource file.
The string displayed when invoking the resource compiler
to build a Microsoft Visual C++ resource file.
If this is not set, then $RCCOM
(the command line) is displayed.
The flags passed to the resource compiler by the RES builder.
An automatically-generated construction variable
containing the command-line options
for specifying directories to be searched
by the resource compiler.
The value of $RCINCFLAGS
is created
by appending $RCINCPREFIX
and $RCINCSUFFIX
to the beginning and end
of each directory in $CPPPATH
.
The prefix (flag) used to specify an include directory
on the resource compiler command line.
This will be appended to the beginning of each directory
in the $CPPPATH
construction variable
when the $RCINCFLAGS
variable is expanded.
The suffix used to specify an include directory
on the resource compiler command line.
This will be appended to the end of each directory
in the $CPPPATH
construction variable
when the $RCINCFLAGS
variable is expanded.
A function that converts a string into a list of Dir instances by searching the repositories.
The program used on Windows systems
to register a newly-built DLL library
whenever the SharedLibrary
builder
is passed a keyword argument of register=1
.
The command line used on Windows systems
to register a newly-built DLL library
whenever the SharedLibrary
builder
is passed a keyword argument of register=1
.
The string displayed when registering a newly-built DLL file.
If this is not set, then $REGSVRCOM
(the command line) is displayed.
Flags passed to the DLL registration program
on Windows systems when a newly-built DLL library is registered.
By default,
this includes the /s
that prevents dialog boxes from popping up
and requiring user attention.
The Java RMI stub compiler.
The command line used to compile stub
and skeleton class files
from Java classes that contain RMI implementations.
Any options specified in the $RMICFLAGS
construction variable
are included on this command line.
The string displayed when compiling
stub and skeleton class files
from Java classes that contain RMI implementations.
If this is not set, then $RMICCOM
(the command line) is displayed.
env = Environment(RMICCOMSTR = "Generating stub/skeleton class files $TARGETS from $SOURCES")
General options passed to the Java RMI stub compiler.
An automatically-generated construction variable
containing the rpath flags to be used when linking
a program with shared libraries.
The value of $_RPATH
is created
by appending $RPATHPREFIX
and $RPATHSUFFIX
to the beginning and end
of each directory in $RPATH
.
A list of paths to search for shared libraries when running programs.
Currently only used in the GNU (gnulink),
IRIX (sgilink) and Sun (sunlink) linkers.
Ignored on platforms and toolchains that don't support it.
Note that the paths added to RPATH
are not transformed by
scons
in any way: if you want an absolute
path, you must make it absolute yourself.
The prefix used to specify a directory to be searched for
shared libraries when running programs.
This will be appended to the beginning of each directory
in the $RPATH
construction variable
when the $_RPATH
variable is automatically generated.
The suffix used to specify a directory to be searched for
shared libraries when running programs.
This will be appended to the end of each directory
in the $RPATH
construction variable
when the $_RPATH
variable is automatically generated.
The RPC protocol compiler.
Options passed to the RPC protocol compiler
when generating client side stubs.
These are in addition to any flags specified in the
$RPCGENFLAGS
construction variable.
General options passed to the RPC protocol compiler.
Options passed to the RPC protocol compiler
when generating a header file.
These are in addition to any flags specified in the
$RPCGENFLAGS
construction variable.
Options passed to the RPC protocol compiler
when generating server side stubs.
These are in addition to any flags specified in the
$RPCGENFLAGS
construction variable.
Options passed to the RPC protocol compiler
when generating XDR routines.
These are in addition to any flags specified in the
$RPCGENFLAGS
construction variable.
A list of the available implicit dependency scanners. New file scanners may be added by appending to this list, although the more flexible approach is to associate scanners with a specific Builder. See the sections "Builder Objects" and "Scanner Objects," below, for more information.
The
(optional) path to the SCons library directory, initialized from the external
environment. If set, this is used to construct a shorter and more efficient
search path in the $MSVSSCONS
command line executed from Microsoft
Visual Studio project files.
The C compiler used for generating shared-library objects.
The command line used to compile a C source file
to a shared-library object file.
Any options specified in the $SHCFLAGS
,
$SHCCFLAGS
and
$CPPFLAGS
construction variables
are included on this command line.
The string displayed when a C source file
is compiled to a shared object file.
If this is not set, then $SHCCCOM
(the command line) is displayed.
env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")
Options that are passed to the C and C++ compilers to generate shared-library objects.
Options that are passed to the C compiler (only; not C++) to generate shared-library objects.
The C++ compiler used for generating shared-library objects.
The command line used to compile a C++ source file
to a shared-library object file.
Any options specified in the $SHCXXFLAGS
and
$CPPFLAGS
construction variables
are included on this command line.
The string displayed when a C++ source file
is compiled to a shared object file.
If this is not set, then $SHCXXCOM
(the command line) is displayed.
env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")
Options that are passed to the C++ compiler to generate shared-library objects.
The name of the compiler to use when compiling D source destined to be in a shared objects.
The name of the compiler to use when compiling D source destined to be in a shared objects.
The name of the compiler to use when compiling D source destined to be in a shared objects.
The command line to use when compiling code to be part of shared objects.
The command line to use when compiling code to be part of shared objects.
The command line to use when compiling code to be part of shared objects.
SHDLIBVERSION.
SHDLIBVERSIONFLAGS.
The linker to use when creating shared objects for code bases include D sources.
The linker to use when creating shared objects for code bases include D sources.
The linker to use when creating shared objects for code bases include D sources.
The command line to use when generating shared objects.
The command line to use when generating shared objects.
The command line to use when generating shared objects.
The list of flags to use when generating a shared object.
The list of flags to use when generating a shared object.
The list of flags to use when generating a shared object.
A string naming the shell program that will be passed to the
$SPAWN
function.
See the
$SPAWN
construction variable for more information.
The Fortran 03 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $SHF03
if you need to use a specific compiler
or compiler version for Fortran 03 files.
The command line used to compile a Fortran 03 source file
to a shared-library object file.
You only need to set $SHF03COM
if you need to use a specific
command line for Fortran 03 files.
You should normally set the $SHFORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 03 source file
is compiled to a shared-library object file.
If this is not set, then $SHF03COM
or $SHFORTRANCOM
(the command line) is displayed.
Options that are passed to the Fortran 03 compiler
to generated shared-library objects.
You only need to set $SHF03FLAGS
if you need to define specific
user options for Fortran 03 files.
You should normally set the $SHFORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
The command line used to compile a Fortran 03 source file to a
shared-library object file
after first running the file through the C preprocessor.
Any options specified in the $SHF03FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $SHF03PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 03 files.
You should normally set the $SHFORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 03 source file
is compiled to a shared-library object file
after first running the file through the C preprocessor.
If this is not set, then $SHF03PPCOM
or $SHFORTRANPPCOM
(the command line) is displayed.
The Fortran 08 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $SHF08
if you need to use a specific compiler
or compiler version for Fortran 08 files.
The command line used to compile a Fortran 08 source file
to a shared-library object file.
You only need to set $SHF08COM
if you need to use a specific
command line for Fortran 08 files.
You should normally set the $SHFORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 08 source file
is compiled to a shared-library object file.
If this is not set, then $SHF08COM
or $SHFORTRANCOM
(the command line) is displayed.
Options that are passed to the Fortran 08 compiler
to generated shared-library objects.
You only need to set $SHF08FLAGS
if you need to define specific
user options for Fortran 08 files.
You should normally set the $SHFORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
The command line used to compile a Fortran 08 source file to a
shared-library object file
after first running the file through the C preprocessor.
Any options specified in the $SHF08FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $SHF08PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 08 files.
You should normally set the $SHFORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 08 source file
is compiled to a shared-library object file
after first running the file through the C preprocessor.
If this is not set, then $SHF08PPCOM
or $SHFORTRANPPCOM
(the command line) is displayed.
The Fortran 77 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $SHF77
if you need to use a specific compiler
or compiler version for Fortran 77 files.
The command line used to compile a Fortran 77 source file
to a shared-library object file.
You only need to set $SHF77COM
if you need to use a specific
command line for Fortran 77 files.
You should normally set the $SHFORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 77 source file
is compiled to a shared-library object file.
If this is not set, then $SHF77COM
or $SHFORTRANCOM
(the command line) is displayed.
Options that are passed to the Fortran 77 compiler
to generated shared-library objects.
You only need to set $SHF77FLAGS
if you need to define specific
user options for Fortran 77 files.
You should normally set the $SHFORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
The command line used to compile a Fortran 77 source file to a
shared-library object file
after first running the file through the C preprocessor.
Any options specified in the $SHF77FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $SHF77PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 77 files.
You should normally set the $SHFORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 77 source file
is compiled to a shared-library object file
after first running the file through the C preprocessor.
If this is not set, then $SHF77PPCOM
or $SHFORTRANPPCOM
(the command line) is displayed.
The Fortran 90 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $SHF90
if you need to use a specific compiler
or compiler version for Fortran 90 files.
The command line used to compile a Fortran 90 source file
to a shared-library object file.
You only need to set $SHF90COM
if you need to use a specific
command line for Fortran 90 files.
You should normally set the $SHFORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 90 source file
is compiled to a shared-library object file.
If this is not set, then $SHF90COM
or $SHFORTRANCOM
(the command line) is displayed.
Options that are passed to the Fortran 90 compiler
to generated shared-library objects.
You only need to set $SHF90FLAGS
if you need to define specific
user options for Fortran 90 files.
You should normally set the $SHFORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
The command line used to compile a Fortran 90 source file to a
shared-library object file
after first running the file through the C preprocessor.
Any options specified in the $SHF90FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $SHF90PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 90 files.
You should normally set the $SHFORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 90 source file
is compiled to a shared-library object file
after first running the file through the C preprocessor.
If this is not set, then $SHF90PPCOM
or $SHFORTRANPPCOM
(the command line) is displayed.
The Fortran 95 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN
variable,
which specifies the default Fortran compiler
for all Fortran versions.
You only need to set $SHF95
if you need to use a specific compiler
or compiler version for Fortran 95 files.
The command line used to compile a Fortran 95 source file
to a shared-library object file.
You only need to set $SHF95COM
if you need to use a specific
command line for Fortran 95 files.
You should normally set the $SHFORTRANCOM
variable,
which specifies the default command line
for all Fortran versions.
The string displayed when a Fortran 95 source file
is compiled to a shared-library object file.
If this is not set, then $SHF95COM
or $SHFORTRANCOM
(the command line) is displayed.
Options that are passed to the Fortran 95 compiler
to generated shared-library objects.
You only need to set $SHF95FLAGS
if you need to define specific
user options for Fortran 95 files.
You should normally set the $SHFORTRANFLAGS
variable,
which specifies the user-specified options
passed to the default Fortran compiler
for all Fortran versions.
The command line used to compile a Fortran 95 source file to a
shared-library object file
after first running the file through the C preprocessor.
Any options specified in the $SHF95FLAGS
and $CPPFLAGS
construction variables
are included on this command line.
You only need to set $SHF95PPCOM
if you need to use a specific
C-preprocessor command line for Fortran 95 files.
You should normally set the $SHFORTRANPPCOM
variable,
which specifies the default C-preprocessor command line
for all Fortran versions.
The string displayed when a Fortran 95 source file
is compiled to a shared-library object file
after first running the file through the C preprocessor.
If this is not set, then $SHF95PPCOM
or $SHFORTRANPPCOM
(the command line) is displayed.
The default Fortran compiler used for generating shared-library objects.
The command line used to compile a Fortran source file to a shared-library object file.
The string displayed when a Fortran source file
is compiled to a shared-library object file.
If this is not set, then $SHFORTRANCOM
(the command line) is displayed.
Options that are passed to the Fortran compiler to generate shared-library objects.
The command line used to compile a Fortran source file to a
shared-library object file
after first running the file through the C preprocessor.
Any options specified
in the $SHFORTRANFLAGS
and
$CPPFLAGS
construction variables
are included on this command line.
The string displayed when a Fortran source file
is compiled to a shared-library object file
after first running the file through the C preprocessor.
If this is not set, then $SHFORTRANPPCOM
(the command line) is displayed.
TODO
Instructs the SharedLibrary
builder to not create symlinks for versioned
shared libraries.
The prefix used for shared library file names.
A macro that automatically generates shared library's SONAME based on $TARGET,
$SHLIBVERSION and $SHLIBSUFFIX. Used by SharedLibrary
builder when
the linker tool supports SONAME (e.g. gnulink
).
The suffix used for shared library file names.
When this construction variable is defined, a versioned shared library
is created by SharedLibrary
builder. This activates the
$_SHLIBVERSIONFLAGS
and thus modifies the $SHLINKCOM
as
required, adds the version number to the library name, and creates the symlinks
that are needed. $SHLIBVERSION
versions should exist as alpha-numeric,
decimal-delimited values as defined by the regular expression "\w+[\.\w+]*".
Example $SHLIBVERSION
values include '1', '1.2.3', and '1.2.gitaa412c8b'.
This macro automatically introduces extra flags to $SHLINKCOM
when
building versioned SharedLibrary
(that is when $SHLIBVERSION
is set). _SHLIBVERSIONFLAGS
usually adds $SHLIBVERSIONFLAGS
and some extra dynamically generated options (such as
-Wl,-soname=$_SHLIBSONAME
. It is unused by "plain"
(unversioned) shared libraries.
Extra flags added to $SHLINKCOM
when building versioned
SharedLibrary
. These flags are only used when $SHLIBVERSION
is
set.
The linker for programs that use shared libraries.
The command line used to link programs using shared libraries.
The string displayed when programs using shared libraries are linked.
If this is not set, then $SHLINKCOM
(the command line) is displayed.
env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")
General user options passed to the linker for programs using shared libraries.
Note that this variable should
not
contain
-l
(or similar) options for linking with the libraries listed in $LIBS
,
nor
-L
(or similar) include search path options
that scons generates automatically from $LIBPATH
.
See
$_LIBFLAGS
above,
for the variable that expands to library-link options,
and
$_LIBDIRFLAGS
above,
for the variable that expands to library search path options.
The prefix used for shared object file names.
The suffix used for shared object file names.
Variable used to hard-code SONAME for versioned shared library/loadable module.
env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SONAME='libtest.so.2')
The variable is used, for example, by gnulink
linker tool.
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
The URL
(web address)
of the location from which the project was retrieved.
This is used to fill in the
Source:
field in the controlling information for Ipkg and RPM packages.
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
A command interpreter function that will be called to execute command line strings. The function must expect the following arguments:
def spawn(shell, escape, cmd, args, env):
sh
is a string naming the shell program to use.
escape
is a function that can be called to escape shell special characters in
the command line.
cmd
is the path to the command to be executed.
args
is the arguments to the command.
env
is a dictionary of the environment variables
in which the command should be executed.
When this variable is true, static objects and shared objects are assumed to be the same; that is, SCons does not check for linking static objects into a shared library.
The dictionary used by the Substfile
or Textfile
builders
for substitution values.
It can be anything acceptable to the dict() constructor,
so in addition to a dictionary,
lists of tuples are also acceptable.
The prefix used for Substfile
file names,
the null string by default.
The suffix used for Substfile
file names,
the null string by default.
A short summary of what the project is about.
This is used to fill in the
Summary:
field in the controlling information for Ipkg and RPM packages,
and as the
Description:
field in MSI packages.
The scripting language wrapper and interface generator.
The suffix that will be used for intermediate C
source files generated by
the scripting language wrapper and interface generator.
The default value is
_wrap
$CFILESUFFIX
.
By default, this value is used whenever the
-c++
option is
not
specified as part of the
$SWIGFLAGS
construction variable.
The command line used to call the scripting language wrapper and interface generator.
The string displayed when calling
the scripting language wrapper and interface generator.
If this is not set, then $SWIGCOM
(the command line) is displayed.
The suffix that will be used for intermediate C++
source files generated by
the scripting language wrapper and interface generator.
The default value is
_wrap
$CFILESUFFIX
.
By default, this value is used whenever the
-c++
option is specified as part of the
$SWIGFLAGS
construction variable.
The suffix that will be used for intermediate C++ header
files generated by the scripting language wrapper and interface generator.
These are only generated for C++ code when the SWIG 'directors' feature is
turned on.
The default value is
_wrap.h
.
General options passed to
the scripting language wrapper and interface generator.
This is where you should set
-python
,
-perl5
,
-tcl
,
or whatever other options you want to specify to SWIG.
If you set the
-c++
option in this variable,
scons
will, by default,
generate a C++ intermediate source file
with the extension that is specified as the
$CXXFILESUFFIX
variable.
An automatically-generated construction variable
containing the SWIG command-line options
for specifying directories to be searched for included files.
The value of $_SWIGINCFLAGS
is created
by appending $SWIGINCPREFIX
and $SWIGINCSUFFIX
to the beginning and end
of each directory in $SWIGPATH
.
The prefix used to specify an include directory on the SWIG command line.
This will be appended to the beginning of each directory
in the $SWIGPATH
construction variable
when the $_SWIGINCFLAGS
variable is automatically generated.
The suffix used to specify an include directory on the SWIG command line.
This will be appended to the end of each directory
in the $SWIGPATH
construction variable
when the $_SWIGINCFLAGS
variable is automatically generated.
Specifies the output directory in which
the scripting language wrapper and interface generator
should place generated language-specific files.
This will be used by SCons to identify
the files that will be generated by the swig call,
and translated into the
swig -outdir
option on the command line.
The list of directories that the scripting language wrapper and interface generate will search for included files. The SWIG implicit dependency scanner will search these directories for include files. The default value is an empty list.
Don't explicitly put include directory
arguments in SWIGFLAGS;
the result will be non-portable
and the directories will not be searched by the dependency scanner.
Note: directory names in SWIGPATH will be looked-up relative to the SConscript
directory when they are used in a command.
To force
scons
to look-up a directory relative to the root of the source tree use #:
env = Environment(SWIGPATH='#/include')
The directory look-up can also be forced using the
Dir
()
function:
include = Dir('include') env = Environment(SWIGPATH=include)
The directory list will be added to command lines
through the automatically-generated
$_SWIGINCFLAGS
construction variable,
which is constructed by
appending the values of the
$SWIGINCPREFIX
and $SWIGINCSUFFIX
construction variables
to the beginning and end
of each directory in $SWIGPATH
.
Any command lines you define that need
the SWIGPATH directory list should
include $_SWIGINCFLAGS
:
env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SOURCES")
The version number of the SWIG tool.
The tar archiver.
The command line used to call the tar archiver.
The string displayed when archiving files
using the tar archiver.
If this is not set, then $TARCOM
(the command line) is displayed.
env = Environment(TARCOMSTR = "Archiving $TARGET")
General options passed to the tar archiver.
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
The name of the target hardware architecture for the compiled objects created by this Environment. This defaults to the value of HOST_ARCH, and the user can override it. Currently only set for Win32.
Sets the target architecture for Visual Studio compiler (i.e. the arch
of the binaries generated by the compiler). If not set, default to
$HOST_ARCH
, or, if that is unset, to the architecture of the
running machine's OS (note that the python build or architecture has no
effect).
This variable must be passed as an argument to the Environment()
constructor; setting it later has no effect.
This is currently only used on Windows, but in the future it will be
used on other OSes as well.
Valid values for Windows are
x86
,
i386
(for 32 bits);
amd64
,
emt64
,
x86_64
(for 64 bits);
and ia64
(Itanium).
For example, if you want to compile 64-bit binaries, you would set
TARGET_ARCH='x86_64'
in your SCons environment.
The name of the target operating system for the compiled objects created by this Environment. This defaults to the value of HOST_OS, and the user can override it. Currently only set for Win32.
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
The suffix used for tar file names.
The prefix for a temporary file used to execute lines longer than $MAXLINELENGTH. The default is '@'. This may be set for toolchains that use other values, such as '-@' for the diab compiler or '-via' for ARM toolchain.
The TeX formatter and typesetter.
The command line used to call the TeX formatter and typesetter.
The string displayed when calling
the TeX formatter and typesetter.
If this is not set, then $TEXCOM
(the command line) is displayed.
env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")
General options passed to the TeX formatter and typesetter.
List of directories that the LaTeX program will search for include directories. The LaTeX implicit dependency scanner will search these directories for \include and \import files.
The prefix used for Textfile
file names,
the null string by default.
The suffix used for Textfile
file names;
.txt
by default.
A list of the names of the Tool specifications that are part of this construction environment.
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)
The person or organization who supply the packaged software.
This is used to fill in the
Vendor:
field in the controlling information for RPM packages,
and the
Manufacturer:
field in the controlling information for MSI packages.
The version of the project, specified as a string.
A deprecated synonym for $WINDOWS_INSERT_DEF
.
A deprecated synonym for $WINDOWSDEFPREFIX
.
A deprecated synonym for $WINDOWSDEFSUFFIX
.
A deprecated synonym for $WINDOWSEXPSUFFIX
.
A deprecated synonym for $WINDOWSEXPSUFFIX
.
Set this variable to True or 1 to embed the compiler-generated manifest
(normally ${TARGET}.manifest
)
into all Windows exes and DLLs built with this environment,
as a resource during their link step.
This is done using $MT
and $MTEXECOM
and $MTSHLIBCOM
.
When this is set to true,
a library build of a Windows shared library
(.dll
file)
will also build a corresponding .def
file
at the same time,
if a .def
file
is not already listed as a build target.
The default is 0 (do not build a .def
file).
When this is set to true,
scons
will be aware of the
.manifest
files generated by Microsoft Visua C/C++ 8.
The prefix used for Windows .def
file names.
The suffix used for Windows .def
file names.
The prefix used for Windows .exp
file names.
The suffix used for Windows .exp
file names.
The prefix used for executable program .manifest
files
generated by Microsoft Visual C/C++.
The suffix used for executable program .manifest
files
generated by Microsoft Visual C/C++.
The prefix used for shared library .manifest
files
generated by Microsoft Visual C/C++.
The suffix used for shared library .manifest
files
generated by Microsoft Visual C/C++.
This is used to fill in the
Depends:
field in the controlling information for Ipkg packages.
This is used to fill in the
Description:
field in the controlling information for Ipkg packages.
The default value is
$SUMMARY\n$DESCRIPTION
This is used to fill in the
Maintainer:
field in the controlling information for Ipkg packages.
This is used to fill in the
Priority:
field in the controlling information for Ipkg packages.
This is used to fill in the
Section:
field in the controlling information for Ipkg packages.
This is used to fill in the
Language:
attribute in the controlling information for MSI packages.
The text of the software license in RTF format. Carriage return characters will be replaced with the RTF equivalent \\par.
TODO
This is used to fill in the
AutoReqProv:
field in the RPM
.spec
file.
internal, but overridable
This is used to fill in the
BuildRequires:
field in the RPM
.spec
file.
internal, but overridable
internal, but overridable
This is used to fill in the
Conflicts:
field in the RPM
.spec
file.
This value is used as the default attributes
for the files in the RPM package.
The default value is
(-,root,root)
.
This is used to fill in the
Distribution:
field in the RPM
.spec
file.
This is used to fill in the
Epoch:
field in the controlling information for RPM packages.
This is used to fill in the
ExcludeArch:
field in the RPM
.spec
file.
This is used to fill in the
ExclusiveArch:
field in the RPM
.spec
file.
This is used to fill in the
Group:
field in the RPM
.spec
file.
This is used to fill in the
Group(lang):
field in the RPM
.spec
file.
Note that
lang
is not literal
and should be replaced by
the appropriate language code.
This is used to fill in the
Icon:
field in the RPM
.spec
file.
internal, but overridable
This is used to fill in the
Packager:
field in the RPM
.spec
file.
This is used to fill in the
%post:
section in the RPM
.spec
file.
This is used to fill in the
%postun:
section in the RPM
.spec
file.
This is used to fill in the
Prefix:
field in the RPM
.spec
file.
This is used to fill in the
%pre:
section in the RPM
.spec
file.
internal, but overridable
This is used to fill in the
%preun:
section in the RPM
.spec
file.
This is used to fill in the
Provides:
field in the RPM
.spec
file.
This is used to fill in the
Requires:
field in the RPM
.spec
file.
This is used to fill in the
Serial:
field in the RPM
.spec
file.
This is used to fill in the
Url:
field in the RPM
.spec
file.
Path to xgettext(1) program (found via
Detect()
).
See xgettext
tool and POTUpdate
builder.
Complete xgettext command line.
See xgettext
tool and POTUpdate
builder.
A string that is shown when xgettext(1) command is invoked
(default: ''
, which means "print $XGETTEXTCOM
").
See xgettext
tool and POTUpdate
builder.
Internal "macro". Generates xgettext domain name
form source and target (default: '${TARGET.filebase}'
).
Additional flags to xgettext(1).
See xgettext
tool and POTUpdate
builder.
Name of file containing list of xgettext(1)'s source
files. Autotools' users know this as POTFILES.in
so they
will in most cases set XGETTEXTFROM="POTFILES.in"
here.
The $XGETTEXTFROM
files have same syntax and semantics as the well known
GNU POTFILES.in
.
See xgettext
tool and POTUpdate
builder.
Internal "macro". Genrates list of -D<dir>
flags
from the $XGETTEXTPATH
list.
This flag is used to add single $XGETTEXTFROM
file to
xgettext(1)'s commandline (default:
'-f'
).
(default: ''
)
List of directories, there xgettext(1) will look for
source files (default: []
).
This variable works only together with $XGETTEXTFROM
Internal "macro". Generates list of -f<file>
flags
from $XGETTEXTFROM
.
This flag is used to add single search path to
xgettext(1)'s commandline (default:
'-D'
).
(default: ''
)
The parser generator.
The command line used to call the parser generator to generate a source file.
The string displayed when generating a source file
using the parser generator.
If this is not set, then $YACCCOM
(the command line) is displayed.
env = Environment(YACCCOMSTR = "Yacc'ing $TARGET from $SOURCES")
General options passed to the parser generator.
If $YACCFLAGS
contains a -d
option,
SCons assumes that the call will also create a .h file
(if the yacc source file ends in a .y suffix)
or a .hpp file
(if the yacc source file ends in a .yy suffix)
The suffix of the C
header file generated by the parser generator
when the
-d
option is used.
Note that setting this variable does not cause
the parser generator to generate a header
file with the specified suffix,
it exists to allow you to specify
what suffix the parser generator will use of its own accord.
The default value is
.h
.
The suffix of the C++
header file generated by the parser generator
when the
-d
option is used.
Note that setting this variable does not cause
the parser generator to generate a header
file with the specified suffix,
it exists to allow you to specify
what suffix the parser generator will use of its own accord.
The default value is
.hpp
,
except on Mac OS X,
where the default is
${TARGET.suffix}.h
.
because the default bison parser generator just
appends .h
to the name of the generated C++ file.
The suffix of the file
containing the VCG grammar automaton definition
when the
--graph=
option is used.
Note that setting this variable does not cause
the parser generator to generate a VCG
file with the specified suffix,
it exists to allow you to specify
what suffix the parser generator will use of its own accord.
The default value is
.vcg
.
The zip compression and file packaging utility.
The command line used to call the zip utility, or the internal Python function used to create a zip archive.
The
compression
flag
from the Python
zipfile
module used by the internal Python function
to control whether the zip archive
is compressed or not.
The default value is
zipfile.ZIP_DEFLATED
,
which creates a compressed zip archive.
This value has no effect if the
zipfile
module is unavailable.
The string displayed when archiving files
using the zip utility.
If this is not set, then $ZIPCOM
(the command line or internal Python function) is displayed.
env = Environment(ZIPCOMSTR = "Zipping $TARGET")
General options passed to the zip utility.
An optional zip root directory (default empty). The filenames stored in the zip file will be relative to this directory, if given. Otherwise the filenames are relative to the current directory of the command. For instance:
env = Environment() env.Zip('foo.zip', 'subdir1/subdir2/file1', ZIPROOT='subdir1')
will produce a zip file foo.zip
containing a file with the name
subdir2/file1
rather than
subdir1/subdir2/file1
.
The suffix used for zip file names.
This appendix contains descriptions of all of the Builders that are potentially available "out of the box" in this version of SCons.
CFile()
,
env.CFile()
Builds a C source file given a lex (.l
)
or yacc (.y
) input file.
The suffix specified by the $CFILESUFFIX
construction variable
(.c
by default)
is automatically added to the target
if it is not already present.
Example:
# builds foo.c env.CFile(target = 'foo.c', source = 'foo.l') # builds bar.c env.CFile(target = 'bar', source = 'bar.y')
Command()
,
env.Command()
The Command
"Builder" is actually implemented
as a function that looks like a Builder,
but actually takes an additional argument of the action
from which the Builder should be made.
See the Command
function description
for the calling syntax and details.
CXXFile()
,
env.CXXFile()
Builds a C++ source file given a lex (.ll
)
or yacc (.yy
)
input file.
The suffix specified by the $CXXFILESUFFIX
construction variable
(.cc
by default)
is automatically added to the target
if it is not already present.
Example:
# builds foo.cc env.CXXFile(target = 'foo.cc', source = 'foo.ll') # builds bar.cc env.CXXFile(target = 'bar', source = 'bar.yy')
DocbookEpub()
,
env.DocbookEpub()
A pseudo-Builder, providing a Docbook toolchain for EPUB output.
env = Environment(tools=['docbook']) env.DocbookEpub('manual.epub', 'manual.xml')
or simply
env = Environment(tools=['docbook']) env.DocbookEpub('manual')
DocbookHtml()
,
env.DocbookHtml()
A pseudo-Builder, providing a Docbook toolchain for HTML output.
env = Environment(tools=['docbook']) env.DocbookHtml('manual.html', 'manual.xml')
or simply
env = Environment(tools=['docbook']) env.DocbookHtml('manual')
DocbookHtmlChunked()
,
env.DocbookHtmlChunked()
A pseudo-Builder, providing a Docbook toolchain for chunked HTML output.
It supports the base.dir
parameter. The
chunkfast.xsl
file (requires "EXSLT") is used as the
default stylesheet. Basic syntax:
env = Environment(tools=['docbook']) env.DocbookHtmlChunked('manual')
where manual.xml
is the input file.
If you use the root.filename
parameter in your own stylesheets you have to specify the new target name.
This ensures that the dependencies get correct, especially for the cleanup via “scons -c
”:
env = Environment(tools=['docbook']) env.DocbookHtmlChunked('mymanual.html', 'manual', xsl='htmlchunk.xsl')
Some basic support for the base.dir
is provided. You
can add the base_dir
keyword to your Builder
call, and the given prefix gets prepended to all the created filenames:
env = Environment(tools=['docbook']) env.DocbookHtmlChunked('manual', xsl='htmlchunk.xsl', base_dir='output/')
Make sure that you don't forget the trailing slash for the base folder, else your files get renamed only!
DocbookHtmlhelp()
,
env.DocbookHtmlhelp()
A pseudo-Builder, providing a Docbook toolchain for HTMLHELP output. Its basic syntax is:
env = Environment(tools=['docbook']) env.DocbookHtmlhelp('manual')
where manual.xml
is the input file.
If you use the root.filename
parameter in your own stylesheets you have to specify the new target name.
This ensures that the dependencies get correct, especially for the cleanup via “scons -c
”:
env = Environment(tools=['docbook']) env.DocbookHtmlhelp('mymanual.html', 'manual', xsl='htmlhelp.xsl')
Some basic support for the base.dir
parameter
is provided. You can add the base_dir
keyword to
your Builder call, and the given prefix gets prepended to all the
created filenames:
env = Environment(tools=['docbook']) env.DocbookHtmlhelp('manual', xsl='htmlhelp.xsl', base_dir='output/')
Make sure that you don't forget the trailing slash for the base folder, else your files get renamed only!
DocbookMan()
,
env.DocbookMan()
A pseudo-Builder, providing a Docbook toolchain for Man page output. Its basic syntax is:
env = Environment(tools=['docbook']) env.DocbookMan('manual')
where manual.xml
is the input file. Note, that
you can specify a target name, but the actual output names are automatically
set from the refname
entries in your XML source.
DocbookPdf()
,
env.DocbookPdf()
A pseudo-Builder, providing a Docbook toolchain for PDF output.
env = Environment(tools=['docbook']) env.DocbookPdf('manual.pdf', 'manual.xml')
or simply
env = Environment(tools=['docbook']) env.DocbookPdf('manual')
DocbookSlidesHtml()
,
env.DocbookSlidesHtml()
A pseudo-Builder, providing a Docbook toolchain for HTML slides output.
env = Environment(tools=['docbook']) env.DocbookSlidesHtml('manual')
If you use the titlefoil.html
parameter in
your own stylesheets you have to give the new target name. This ensures
that the dependencies get correct, especially for the cleanup via
“scons -c
”:
env = Environment(tools=['docbook']) env.DocbookSlidesHtml('mymanual.html','manual', xsl='slideshtml.xsl')
Some basic support for the base.dir
parameter
is provided. You
can add the base_dir
keyword to your Builder
call, and the given prefix gets prepended to all the created filenames:
env = Environment(tools=['docbook']) env.DocbookSlidesHtml('manual', xsl='slideshtml.xsl', base_dir='output/')
Make sure that you don't forget the trailing slash for the base folder, else your files get renamed only!
DocbookSlidesPdf()
,
env.DocbookSlidesPdf()
A pseudo-Builder, providing a Docbook toolchain for PDF slides output.
env = Environment(tools=['docbook']) env.DocbookSlidesPdf('manual.pdf', 'manual.xml')
or simply
env = Environment(tools=['docbook']) env.DocbookSlidesPdf('manual')
DocbookXInclude()
,
env.DocbookXInclude()
A pseudo-Builder, for resolving XIncludes in a separate processing step.
env = Environment(tools=['docbook']) env.DocbookXInclude('manual_xincluded.xml', 'manual.xml')
DocbookXslt()
,
env.DocbookXslt()
A pseudo-Builder, applying a given XSL transformation to the input file.
env = Environment(tools=['docbook']) env.DocbookXslt('manual_transformed.xml', 'manual.xml', xsl='transform.xslt')
Note, that this builder requires the xsl
parameter
to be set.
DVI()
,
env.DVI()
Builds a .dvi
file
from a .tex
,
.ltx
or .latex
input file.
If the source file suffix is .tex
,
scons
will examine the contents of the file;
if the string
\documentclass
or
\documentstyle
is found, the file is assumed to be a LaTeX file and
the target is built by invoking the $LATEXCOM
command line;
otherwise, the $TEXCOM
command line is used.
If the file is a LaTeX file,
the
DVI
builder method will also examine the contents
of the
.aux
file and invoke the $BIBTEX
command line
if the string
bibdata
is found,
start $MAKEINDEX
to generate an index if a
.ind
file is found
and will examine the contents
.log
file and re-run the $LATEXCOM
command
if the log file says it is necessary.
The suffix .dvi
(hard-coded within TeX itself)
is automatically added to the target
if it is not already present.
Examples:
# builds from aaa.tex env.DVI(target = 'aaa.dvi', source = 'aaa.tex') # builds bbb.dvi env.DVI(target = 'bbb', source = 'bbb.ltx') # builds from ccc.latex env.DVI(target = 'ccc.dvi', source = 'ccc.latex')
Gs()
,
env.Gs()
A Builder for explicitly calling the gs
executable.
Depending on the underlying OS, the different names gs
,
gsos2
and gswin32c
are tried.
env = Environment(tools=['gs']) env.Gs('cover.jpg','scons-scons.pdf', GSFLAGS='-dNOPAUSE -dBATCH -sDEVICE=jpeg -dFirstPage=1 -dLastPage=1 -q') )
Install()
,
env.Install()
Installs one or more source files or directories in the specified target, which must be a directory. The names of the specified source files or directories remain the same within the destination directory. The sources may be given as a string or as a node returned by a builder.
env.Install('/usr/local/bin', source = ['foo', 'bar'])
InstallAs()
,
env.InstallAs()
Installs one or more source files or directories to specific names, allowing changing a file or directory name as part of the installation. It is an error if the target and source arguments list different numbers of files or directories.
env.InstallAs(target = '/usr/local/bin/foo', source = 'foo_debug') env.InstallAs(target = ['../lib/libfoo.a', '../lib/libbar.a'], source = ['libFOO.a', 'libBAR.a'])
InstallVersionedLib()
,
env.InstallVersionedLib()
Installs a versioned shared library. The symlinks appropriate to the architecture will be generated based on symlinks of the source library.
env.InstallVersionedLib(target = '/usr/local/bin/foo', source = 'libxyz.1.5.2.so')
Jar()
,
env.Jar()
Builds a Java archive (.jar
) file
from the specified list of sources.
Any directories in the source list
will be searched for .class
files).
Any .java
files in the source list
will be compiled to .class
files
by calling the Java
Builder.
If the $JARCHDIR
value is set, the
jar
command will change to the specified directory using the
-C
option.
If $JARCHDIR
is not set explicitly,
SCons will use the top of any subdirectory tree
in which Java .class
were built by the Java
Builder.
If the contents any of the source files begin with the string
Manifest-Version
,
the file is assumed to be a manifest
and is passed to the
jar
command with the
m
option set.
env.Jar(target = 'foo.jar', source = 'classes') env.Jar(target = 'bar.jar', source = ['bar1.java', 'bar2.java'])
Java()
,
env.Java()
Builds one or more Java class files.
The sources may be any combination of explicit
.java
files,
or directory trees which will be scanned
for .java
files.
SCons will parse each source .java
file
to find the classes
(including inner classes)
defined within that file,
and from that figure out the
target .class
files that will be created.
The class files will be placed underneath
the specified target directory.
SCons will also search each Java file
for the Java package name,
which it assumes can be found on a line
beginning with the string
package
in the first column;
the resulting .class
files
will be placed in a directory reflecting
the specified package name.
For example,
the file
Foo.java
defining a single public
Foo
class and
containing a package name of
sub.dir
will generate a corresponding
sub/dir/Foo.class
class file.
Examples:
env.Java(target = 'classes', source = 'src') env.Java(target = 'classes', source = ['src1', 'src2']) env.Java(target = 'classes', source = ['File1.java', 'File2.java'])
Java source files can use the native encoding for the underlying OS.
Since SCons compiles in simple ASCII mode by default,
the compiler will generate warnings about unmappable characters,
which may lead to errors as the file is processed further.
In this case, the user must specify the LANG
environment variable to tell the compiler what encoding is used.
For portibility, it's best if the encoding is hard-coded
so that the compile will work if it is done on a system
with a different encoding.
env = Environment() env['ENV']['LANG'] = 'en_GB.UTF-8'
JavaH()
,
env.JavaH()
Builds C header and source files for
implementing Java native methods.
The target can be either a directory
in which the header files will be written,
or a header file name which
will contain all of the definitions.
The source can be the names of .class
files,
the names of .java
files
to be compiled into .class
files
by calling the Java
builder method,
or the objects returned from the
Java
builder method.
If the construction variable
$JAVACLASSDIR
is set, either in the environment
or in the call to the
JavaH
builder method itself,
then the value of the variable
will be stripped from the
beginning of any .class
file names.
Examples:
# builds java_native.h classes = env.Java(target = 'classdir', source = 'src') env.JavaH(target = 'java_native.h', source = classes) # builds include/package_foo.h and include/package_bar.h env.JavaH(target = 'include', source = ['package/foo.class', 'package/bar.class']) # builds export/foo.h and export/bar.h env.JavaH(target = 'export', source = ['classes/foo.class', 'classes/bar.class'], JAVACLASSDIR = 'classes')
Library()
,
env.Library()
A synonym for the
StaticLibrary
builder method.
LoadableModule()
,
env.LoadableModule()
On most systems,
this is the same as
SharedLibrary
.
On Mac OS X (Darwin) platforms,
this creates a loadable module bundle.
M4()
,
env.M4()
Builds an output file from an M4 input file.
This uses a default $M4FLAGS
value of
-E
,
which considers all warnings to be fatal
and stops on the first warning
when using the GNU version of m4.
Example:
env.M4(target = 'foo.c', source = 'foo.c.m4')
Moc()
,
env.Moc()
Builds an output file from a moc input file. Moc input files are either
header files or cxx files. This builder is only available after using the
tool 'qt'. See the $QTDIR
variable for more information.
Example:
env.Moc('foo.h') # generates moc_foo.cc env.Moc('foo.cpp') # generates foo.moc
MOFiles()
,
env.MOFiles()
This builder belongs to msgfmt
tool. The builder compiles
PO
files to MO
files.
Example 1.
Create pl.mo
and en.mo
by compiling
pl.po
and en.po
:
# ... env.MOFiles(['pl', 'en'])
Example 2.
Compile files for languages defined in LINGUAS
file:
# ... env.MOFiles(LINGUAS_FILE = 1)
Example 3.
Create pl.mo
and en.mo
by compiling
pl.po
and en.po
plus files for
languages defined in LINGUAS
file:
# ... env.MOFiles(['pl', 'en'], LINGUAS_FILE = 1)
Example 4.
Compile files for languages defined in LINGUAS
file
(another version):
# ... env['LINGUAS_FILE'] = 1 env.MOFiles()
MSVSProject()
,
env.MSVSProject()
Builds a Microsoft Visual Studio project file, and by default builds a solution file as well.
This
builds a Visual Studio project file, based on the version of Visual Studio
that is configured (either the latest installed version, or the version
specified by $MSVS_VERSION
in the Environment constructor). For
Visual Studio 6, it will generate a .dsp
file. For Visual
Studio 7 (.NET) and later versions, it will generate a
.vcproj
file.
By default, this also
generates a solution file for the specified project, a
.dsw
file for Visual Studio 6 or a
.sln
file for Visual Studio 7 (.NET). This behavior may
be disabled by specifying auto_build_solution=0
when you
call MSVSProject
, in which case you presumably want to build the solution
file(s) by calling the MSVSSolution
Builder (see below).
The MSVSProject
builder takes several lists of filenames to be placed into
the project file. These are currently limited to srcs
,
incs
, localincs
,
resources
, and misc
. These are pretty
self-explanatory, but it should be noted that these lists are added to the
$SOURCES
construction variable as strings, NOT as SCons File Nodes.
This is because they represent file names to be added to the project file, not
the source files used to build the project file.
The above filename lists are all optional, although at least one must be specified for the resulting project file to be non-empty.
In addition to the above lists of values, the following values may be specified:
The name of the target .dsp
or
.vcproj
file. The correct suffix for the version
of Visual Studio must be used, but the $MSVSPROJECTSUFFIX
construction variable will be defined to the correct value (see
example below).
The name of this particular variant. For Visual Studio 7
projects, this can also be a list of variant names. These are
typically things like "Debug" or "Release", but really can be anything
you want. For Visual Studio 7 projects, they may also specify a target
platform separated from the variant name by a |
(vertical pipe) character: Debug|Xbox
. The default
target platform is Win32. Multiple calls to MSVSProject
with
different variants are allowed; all variants will be added to the
project file with their appropriate build targets and
sources.
Additional command line arguments for the different
variants. The number of cmdargs
entries must match
the number of variant
entries, or be empty (not
specified). If you give only one, it will automatically be propagated
to all variants.
An optional string, node, or list of strings or nodes (one
per build variant), to tell the Visual Studio debugger what output
target to use in what build variant. The number of
buildtarget
entries must match the number of
variant
entries.
The name of the file that Visual Studio 7 and later will
run and debug. This appears as the value of the
Output
field in the resulting Visual Studio project
file. If this is not specified, the default is the same as the
specified buildtarget
value.
Note that because SCons always executes its build
commands from the directory in which the SConstruct
file is located, if you
generate a project file in a different directory than the SConstruct
directory, users will not be able to double-click on the file name in
compilation error messages displayed in the Visual Studio console output
window. This can be remedied by adding the Visual C/C++ /FC
compiler option to the $CCFLAGS
variable so that the compiler will
print the full path name of any files that cause compilation errors.
Example usage:
barsrcs = ['bar.cpp'] barincs = ['bar.h'] barlocalincs = ['StdAfx.h'] barresources = ['bar.rc','resource.h'] barmisc = ['bar_readme.txt'] dll = env.SharedLibrary(target = 'bar.dll', source = barsrcs) buildtarget = [s for s in dll if str(s).endswith('dll')] env.MSVSProject(target = 'Bar' + env['MSVSPROJECTSUFFIX'], srcs = barsrcs, incs = barincs, localincs = barlocalincs, resources = barresources, misc = barmisc, buildtarget = buildtarget, variant = 'Release')
Starting with version 2.4 of
SCons it's also possible to specify the optional argument
DebugSettings
, which creates files for debugging under
Visual Studio:
A dictionary of debug settings that get written to the
.vcproj.user
or the
.vcxproj.user
file, depending on the version
installed. As it is done for cmdargs (see above), you can specify a
DebugSettings
dictionary per variant. If you
give only one, it will be propagated to all variants.
Currently, only Visual Studio v9.0 and Visual Studio
version v11 are implemented, for other versions no file is generated. To
generate the user file, you just need to add a
DebugSettings
dictionary to the environment with the
right parameters for your MSVS version. If the dictionary is empty, or does
not contain any good value, no file will be generated.
Following is a more contrived example, involving the setup of a project for variants and DebugSettings:
# Assuming you store your defaults in a file vars = Variables('variables.py') msvcver = vars.args.get('vc', '9') # Check command args to force one Microsoft Visual Studio version if msvcver == '9' or msvcver == '11': env = Environment(MSVC_VERSION=msvcver+'.0', MSVC_BATCH=False) else: env = Environment() AddOption('--userfile', action='store_true', dest='userfile', default=False, help="Create Visual Studio Project user file") # # 1. Configure your Debug Setting dictionary with options you want in the list # of allowed options, for instance if you want to create a user file to launch # a specific application for testing your dll with Microsoft Visual Studio 2008 (v9): # V9DebugSettings = { 'Command':'c:\\myapp\\using\\thisdll.exe', 'WorkingDirectory': 'c:\\myapp\\using\\', 'CommandArguments': '-p password', # 'Attach':'false', # 'DebuggerType':'3', # 'Remote':'1', # 'RemoteMachine': None, # 'RemoteCommand': None, # 'HttpUrl': None, # 'PDBPath': None, # 'SQLDebugging': None, # 'Environment': '', # 'EnvironmentMerge':'true', # 'DebuggerFlavor': None, # 'MPIRunCommand': None, # 'MPIRunArguments': None, # 'MPIRunWorkingDirectory': None, # 'ApplicationCommand': None, # 'ApplicationArguments': None, # 'ShimCommand': None, # 'MPIAcceptMode': None, # 'MPIAcceptFilter': None, } # # 2. Because there are a lot of different options depending on the Microsoft # Visual Studio version, if you use more than one version you have to # define a dictionary per version, for instance if you want to create a user # file to launch a specific application for testing your dll with Microsoft # Visual Studio 2012 (v11): # V10DebugSettings = { 'LocalDebuggerCommand': 'c:\\myapp\\using\\thisdll.exe', 'LocalDebuggerWorkingDirectory': 'c:\\myapp\\using\\', 'LocalDebuggerCommandArguments': '-p password', # 'LocalDebuggerEnvironment': None, # 'DebuggerFlavor': 'WindowsLocalDebugger', # 'LocalDebuggerAttach': None, # 'LocalDebuggerDebuggerType': None, # 'LocalDebuggerMergeEnvironment': None, # 'LocalDebuggerSQLDebugging': None, # 'RemoteDebuggerCommand': None, # 'RemoteDebuggerCommandArguments': None, # 'RemoteDebuggerWorkingDirectory': None, # 'RemoteDebuggerServerName': None, # 'RemoteDebuggerConnection': None, # 'RemoteDebuggerDebuggerType': None, # 'RemoteDebuggerAttach': None, # 'RemoteDebuggerSQLDebugging': None, # 'DeploymentDirectory': None, # 'AdditionalFiles': None, # 'RemoteDebuggerDeployDebugCppRuntime': None, # 'WebBrowserDebuggerHttpUrl': None, # 'WebBrowserDebuggerDebuggerType': None, # 'WebServiceDebuggerHttpUrl': None, # 'WebServiceDebuggerDebuggerType': None, # 'WebServiceDebuggerSQLDebugging': None, } # # 3. Select the dictionary you want depending on the version of visual Studio # Files you want to generate. # if not env.GetOption('userfile'): dbgSettings = None elif env.get('MSVC_VERSION', None) == '9.0': dbgSettings = V9DebugSettings elif env.get('MSVC_VERSION', None) == '11.0': dbgSettings = V10DebugSettings else: dbgSettings = None # # 4. Add the dictionary to the DebugSettings keyword. # barsrcs = ['bar.cpp', 'dllmain.cpp', 'stdafx.cpp'] barincs = ['targetver.h'] barlocalincs = ['StdAfx.h'] barresources = ['bar.rc','resource.h'] barmisc = ['ReadMe.txt'] dll = env.SharedLibrary(target = 'bar.dll', source = barsrcs) env.MSVSProject(target = 'Bar' + env['MSVSPROJECTSUFFIX'], srcs = barsrcs, incs = barincs, localincs = barlocalincs, resources = barresources, misc = barmisc, buildtarget = [dll[0]] * 2, variant = ('Debug|Win32', 'Release|Win32'), cmdargs = 'vc=%s' % msvcver, DebugSettings = (dbgSettings, {}))
MSVSSolution()
,
env.MSVSSolution()
Builds a Microsoft Visual Studio solution file.
This builds a Visual Studio solution file, based on the
version of Visual Studio that is configured (either the latest installed
version, or the version specified by $MSVS_VERSION
in the
construction environment). For Visual Studio 6, it will generate a
.dsw
file. For Visual Studio 7 (.NET), it will generate a
.sln
file.
The following values must be specified:
The name of the target .dsw or .sln file. The correct
suffix for the version of Visual Studio must be used, but the value
$MSVSSOLUTIONSUFFIX
will be defined to the correct value (see
example below).
The name of this particular variant, or a list of variant names (the latter is only supported for MSVS 7 solutions). These are typically things like "Debug" or "Release", but really can be anything you want. For MSVS 7 they may also specify target platform, like this "Debug|Xbox". Default platform is Win32.
A list of project file names, or Project nodes returned by
calls to the MSVSProject
Builder, to be placed into the solution
file. It should be noted that these file names are NOT added to the
$SOURCES environment variable in form of files, but rather as strings.
This is because they represent file names to be added to the solution
file, not the source files used to build the solution
file.
Example Usage:
env.MSVSSolution(target = 'Bar' + env['MSVSSOLUTIONSUFFIX'], projects = ['bar' + env['MSVSPROJECTSUFFIX']], variant = 'Release')
Object()
,
env.Object()
A synonym for the
StaticObject
builder method.
Package()
,
env.Package()
Builds a Binary Package of the given source files.
env.Package(source = FindInstalledFiles())
Builds software distribution packages.
Packages consist of files to install and packaging information.
The former may be specified with the source
parameter and may be left out,
in which case the FindInstalledFiles
function will collect
all files that have an Install
or InstallAs
Builder attached.
If the target
is not specified
it will be deduced from additional information given to this Builder.
The packaging information is specified
with the help of construction variables documented below.
This information is called a tag to stress that
some of them can also be attached to files with the Tag
function.
The mandatory ones will complain if they were not specified.
They vary depending on chosen target packager.
The target packager may be selected with the "PACKAGETYPE" command line
option or with the $PACKAGETYPE
construction variable. Currently
the following packagers available:
* msi - Microsoft Installer * rpm - Redhat Package Manger * ipkg - Itsy Package Management System * tarbz2 - compressed tar * targz - compressed tar * zip - zip file * src_tarbz2 - compressed tar source * src_targz - compressed tar source * src_zip - zip file source
An updated list is always available under the "package_type" option when running "scons --help" on a project that has packaging activated.
env = Environment(tools=['default', 'packaging']) env.Install('/bin/', 'my_program') env.Package( NAME = 'foo', VERSION = '1.2.3', PACKAGEVERSION = 0, PACKAGETYPE = 'rpm', LICENSE = 'gpl', SUMMARY = 'balalalalal', DESCRIPTION = 'this should be really really long', X_RPM_GROUP = 'Application/fu', SOURCE_URL = 'http://foo.org/foo-1.2.3.tar.gz' )
PCH()
,
env.PCH()
Builds a Microsoft Visual C++ precompiled header. Calling this builder method returns a list of two targets: the PCH as the first element, and the object file as the second element. Normally the object file is ignored. This builder method is only provided when Microsoft Visual C++ is being used as the compiler. The PCH builder method is generally used in conjunction with the PCH construction variable to force object files to use the precompiled header:
env['PCH'] = env.PCH('StdAfx.cpp')[0]
PDF()
,
env.PDF()
Builds a .pdf
file
from a .dvi
input file
(or, by extension, a .tex
,
.ltx
,
or
.latex
input file).
The suffix specified by the $PDFSUFFIX
construction variable
(.pdf
by default)
is added automatically to the target
if it is not already present. Example:
# builds from aaa.tex env.PDF(target = 'aaa.pdf', source = 'aaa.tex') # builds bbb.pdf from bbb.dvi env.PDF(target = 'bbb', source = 'bbb.dvi')
POInit()
,
env.POInit()
This builder belongs to msginit
tool. The builder initializes missing
PO
file(s) if $POAUTOINIT
is set. If
$POAUTOINIT
is not set (default), POInit
prints instruction for
user (that is supposed to be a translator), telling how the
PO
file should be initialized. In normal projects
you should not use POInit
and use POUpdate
instead. POUpdate
chooses intelligently between
msgmerge(1) and msginit(1). POInit
always uses msginit(1) and should be regarded as builder for
special purposes or for temporary use (e.g. for quick, one time initialization
of a bunch of PO
files) or for tests.
Target nodes defined through POInit
are not built by default (they're
Ignore
d from '.'
node) but are added to
special Alias
('po-create'
by default).
The alias name may be changed through the $POCREATE_ALIAS
construction variable. All PO
files defined through
POInit
may be easily initialized by scons po-create.
Example 1.
Initialize en.po
and pl.po
from
messages.pot
:
# ... env.POInit(['en', 'pl']) # messages.pot --> [en.po, pl.po]
Example 2.
Initialize en.po
and pl.po
from
foo.pot
:
# ... env.POInit(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.po]
Example 3.
Initialize en.po
and pl.po
from
foo.pot
but using $POTDOMAIN
construction
variable:
# ... env.POInit(['en', 'pl'], POTDOMAIN='foo') # foo.pot --> [en.po, pl.po]
Example 4.
Initialize PO
files for languages defined in
LINGUAS
file. The files will be initialized from template
messages.pot
:
# ... env.POInit(LINGUAS_FILE = 1) # needs 'LINGUAS' file
Example 5.
Initialize en.po
and pl.pl
PO
files plus files for languages defined in
LINGUAS
file. The files will be initialized from template
messages.pot
:
# ... env.POInit(['en', 'pl'], LINGUAS_FILE = 1)
Example 6.
You may preconfigure your environment first, and then initialize
PO
files:
# ... env['POAUTOINIT'] = 1 env['LINGUAS_FILE'] = 1 env['POTDOMAIN'] = 'foo' env.POInit()
which has same efect as:
# ... env.POInit(POAUTOINIT = 1, LINGUAS_FILE = 1, POTDOMAIN = 'foo')
PostScript()
,
env.PostScript()
Builds a .ps
file
from a .dvi
input file
(or, by extension, a .tex
,
.ltx
,
or
.latex
input file).
The suffix specified by the $PSSUFFIX
construction variable
(.ps
by default)
is added automatically to the target
if it is not already present. Example:
# builds from aaa.tex env.PostScript(target = 'aaa.ps', source = 'aaa.tex') # builds bbb.ps from bbb.dvi env.PostScript(target = 'bbb', source = 'bbb.dvi')
POTUpdate()
,
env.POTUpdate()
The builder belongs to xgettext
tool. The builder updates target
POT
file if exists or creates one if it doesn't. The node is
not built by default (i.e. it is Ignore
d from
'.'
), but only on demand (i.e. when given
POT
file is required or when special alias is invoked). This
builder adds its targe node (messages.pot
, say) to a
special alias (pot-update
by default, see
$POTUPDATE_ALIAS
) so you can update/create them easily with
scons pot-update. The file is not written until there is no
real change in internationalized messages (or in comments that enter
POT
file).
You may see xgettext(1) being invoked by the
xgettext
tool even if there is no real change in internationalized
messages (so the POT
file is not being updated). This
happens every time a source file has changed. In such case we invoke
xgettext(1) and compare its output with the content of
POT
file to decide whether the file should be updated or
not.
Example 1.
Let's create po/
directory and place following
SConstruct
script there:
# SConstruct in 'po/' subdir env = Environment( tools = ['default', 'xgettext'] ) env.POTUpdate(['foo'], ['../a.cpp', '../b.cpp']) env.POTUpdate(['bar'], ['../c.cpp', '../d.cpp'])
Then invoke scons few times:
user@host:$ scons # Does not create foo.pot nor bar.pot user@host:$ scons foo.pot # Updates or creates foo.pot user@host:$ scons pot-update # Updates or creates foo.pot and bar.pot user@host:$ scons -c # Does not clean foo.pot nor bar.pot.
the results shall be as the comments above say.
Example 2.
The POTUpdate
builder may be used with no target specified, in which
case default target messages.pot
will be used. The
default target may also be overridden by setting $POTDOMAIN
construction
variable or providing it as an override to POTUpdate
builder:
# SConstruct script env = Environment( tools = ['default', 'xgettext'] ) env['POTDOMAIN'] = "foo" env.POTUpdate(source = ["a.cpp", "b.cpp"]) # Creates foo.pot ... env.POTUpdate(POTDOMAIN = "bar", source = ["c.cpp", "d.cpp"]) # and bar.pot
Example 3.
The sources may be specified within separate file, for example
POTFILES.in
:
# POTFILES.in in 'po/' subdirectory ../a.cpp ../b.cpp # end of file
The name of the file (POTFILES.in
) containing the list of
sources is provided via $XGETTEXTFROM
:
# SConstruct file in 'po/' subdirectory env = Environment( tools = ['default', 'xgettext'] ) env.POTUpdate(XGETTEXTFROM = 'POTFILES.in')
Example 4.
You may use $XGETTEXTPATH
to define source search path. Assume, for
example, that you have files a.cpp
,
b.cpp
, po/SConstruct
,
po/POTFILES.in
. Then your POT
-related
files could look as below:
# POTFILES.in in 'po/' subdirectory a.cpp b.cpp # end of file
# SConstruct file in 'po/' subdirectory env = Environment( tools = ['default', 'xgettext'] ) env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH='../')
Example 5.
Multiple search directories may be defined within a list, i.e.
XGETTEXTPATH = ['dir1', 'dir2', ...]
. The order in the list
determines the search order of source files. The path to the first file found
is used.
Let's create 0/1/po/SConstruct
script:
# SConstruct file in '0/1/po/' subdirectory env = Environment( tools = ['default', 'xgettext'] ) env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../', '../../'])
and 0/1/po/POTFILES.in
:
# POTFILES.in in '0/1/po/' subdirectory a.cpp # end of file
Write two *.cpp
files, the first one is
0/a.cpp
:
/* 0/a.cpp */ gettext("Hello from ../../a.cpp")
and the second is 0/1/a.cpp
:
/* 0/1/a.cpp */ gettext("Hello from ../a.cpp")
then run scons. You'll obtain 0/1/po/messages.pot
with the
message "Hello from ../a.cpp"
. When you reverse order in
$XGETTEXTFOM
, i.e. when you write SConscript as
# SConstruct file in '0/1/po/' subdirectory env = Environment( tools = ['default', 'xgettext'] ) env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../../', '../'])
then the messages.pot
will contain
msgid "Hello from ../../a.cpp"
line and not
msgid "Hello from ../a.cpp"
.
POUpdate()
,
env.POUpdate()
The builder belongs to msgmerge
tool. The builder updates
PO
files with msgmerge(1), or initializes
missing PO
files as described in documentation of
msginit
tool and POInit
builder (see also
$POAUTOINIT
). Note, that POUpdate
does not add its
targets to po-create
alias as POInit
does.
Target nodes defined through POUpdate
are not built by default
(they're Ignore
d from '.'
node). Instead,
they are added automatically to special Alias
('po-update'
by default). The alias name may be changed
through the $POUPDATE_ALIAS
construction variable. You can easily
update PO
files in your project by scons
po-update.
Example 1.
Update en.po
and pl.po
from
messages.pot
template (see also $POTDOMAIN
),
assuming that the later one exists or there is rule to build it (see
POTUpdate
):
# ... env.POUpdate(['en','pl']) # messages.pot --> [en.po, pl.po]
Example 2.
Update en.po
and pl.po
from
foo.pot
template:
# ... env.POUpdate(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.pl]
Example 3.
Update en.po
and pl.po
from
foo.pot
(another version):
# ... env.POUpdate(['en', 'pl'], POTDOMAIN='foo') # foo.pot -- > [en.po, pl.pl]
Example 4.
Update files for languages defined in LINGUAS
file. The
files are updated from messages.pot
template:
# ... env.POUpdate(LINGUAS_FILE = 1) # needs 'LINGUAS' file
Example 5.
Same as above, but update from foo.pot
template:
# ... env.POUpdate(LINGUAS_FILE = 1, source = ['foo'])
Example 6.
Update en.po
and pl.po
plus files for
languages defined in LINGUAS
file. The files are updated
from messages.pot
template:
# produce 'en.po', 'pl.po' + files defined in 'LINGUAS': env.POUpdate(['en', 'pl' ], LINGUAS_FILE = 1)
Example 7.
Use $POAUTOINIT
to automatically initialize PO
file
if it doesn't exist:
# ... env.POUpdate(LINGUAS_FILE = 1, POAUTOINIT = 1)
Example 8.
Update PO
files for languages defined in
LINGUAS
file. The files are updated from
foo.pot
template. All necessary settings are
pre-configured via environment.
# ... env['POAUTOINIT'] = 1 env['LINGUAS_FILE'] = 1 env['POTDOMAIN'] = 'foo' env.POUpdate()
Program()
,
env.Program()
Builds an executable given one or more object files
or C, C++, D, or Fortran source files.
If any C, C++, D or Fortran source files are specified,
then they will be automatically
compiled to object files using the
Object
builder method;
see that builder method's description for
a list of legal source file suffixes
and how they are interpreted.
The target executable file prefix
(specified by the $PROGPREFIX
construction variable; nothing by default)
and suffix
(specified by the $PROGSUFFIX
construction variable;
by default, .exe
on Windows systems,
nothing on POSIX systems)
are automatically added to the target if not already present.
Example:
env.Program(target = 'foo', source = ['foo.o', 'bar.c', 'baz.f'])
ProgramAllAtOnce()
,
env.ProgramAllAtOnce()
Builds an executable from D sources without first creating individual objects for each file.
D sources can be compiled file-by-file as C and C++ source are, and
D is integrated into the scons
Object and Program builders for
this model of build. D codes can though do whole source
meta-programming (some of the testing frameworks do this). For this
it is imperative that all sources are compiled and linked in a single call of
the D compiler. This builder serves that purpose.
env.ProgramAllAtOnce('executable', ['mod_a.d, mod_b.d', 'mod_c.d'])
This command will compile the modules mod_a, mod_b, and mod_c in a single compilation process without first creating object files for the modules. Some of the D compilers will create executable.o others will not.
Builds an executable from D sources without first creating individual objects for each file.
D sources can be compiled file-by-file as C and C++ source are, and
D is integrated into the scons
Object and Program builders for
this model of build. D codes can though do whole source
meta-programming (some of the testing frameworks do this). For this
it is imperative that all sources are compiled and linked in a single call of
the D compiler. This builder serves that purpose.
env.ProgramAllAtOnce('executable', ['mod_a.d, mod_b.d', 'mod_c.d'])
This command will compile the modules mod_a, mod_b, and mod_c in a single compilation process without first creating object files for the modules. Some of the D compilers will create executable.o others will not.
Builds an executable from D sources without first creating individual objects for each file.
D sources can be compiled file-by-file as C and C++ source are, and
D is integrated into the scons
Object and Program builders for
this model of build. D codes can though do whole source
meta-programming (some of the testing frameworks do this). For this
it is imperative that all sources are compiled and linked in a single call of
the D compiler. This builder serves that purpose.
env.ProgramAllAtOnce('executable', ['mod_a.d, mod_b.d', 'mod_c.d'])
This command will compile the modules mod_a, mod_b, and mod_c in a single compilation process without first creating object files for the modules. Some of the D compilers will create executable.o others will not.
RES()
,
env.RES()
Builds a Microsoft Visual C++ resource file.
This builder method is only provided
when Microsoft Visual C++ or MinGW is being used as the compiler. The
.res
(or
.o
for MinGW) suffix is added to the target name if no other suffix is given.
The source
file is scanned for implicit dependencies as though it were a C file.
Example:
env.RES('resource.rc')
RMIC()
,
env.RMIC()
Builds stub and skeleton class files
for remote objects
from Java .class
files.
The target is a directory
relative to which the stub
and skeleton class files will be written.
The source can be the names of .class
files,
or the objects return from the
Java
builder method.
If the construction variable
$JAVACLASSDIR
is set, either in the environment
or in the call to the
RMIC
builder method itself,
then the value of the variable
will be stripped from the
beginning of any .class
file names.
classes = env.Java(target = 'classdir', source = 'src') env.RMIC(target = 'outdir1', source = classes) env.RMIC(target = 'outdir2', source = ['package/foo.class', 'package/bar.class']) env.RMIC(target = 'outdir3', source = ['classes/foo.class', 'classes/bar.class'], JAVACLASSDIR = 'classes')
RPCGenClient()
,
env.RPCGenClient()
Generates an RPC client stub (_clnt.c
) file
from a specified RPC (.x
) source file.
Because rpcgen only builds output files
in the local directory,
the command will be executed
in the source file's directory by default.
# Builds src/rpcif_clnt.c env.RPCGenClient('src/rpcif.x')
RPCGenHeader()
,
env.RPCGenHeader()
Generates an RPC header (.h
) file
from a specified RPC (.x
) source file.
Because rpcgen only builds output files
in the local directory,
the command will be executed
in the source file's directory by default.
# Builds src/rpcif.h env.RPCGenHeader('src/rpcif.x')
RPCGenService()
,
env.RPCGenService()
Generates an RPC server-skeleton (_svc.c
) file
from a specified RPC (.x
) source file.
Because rpcgen only builds output files
in the local directory,
the command will be executed
in the source file's directory by default.
# Builds src/rpcif_svc.c env.RPCGenClient('src/rpcif.x')
RPCGenXDR()
,
env.RPCGenXDR()
Generates an RPC XDR routine (_xdr.c
) file
from a specified RPC (.x
) source file.
Because rpcgen only builds output files
in the local directory,
the command will be executed
in the source file's directory by default.
# Builds src/rpcif_xdr.c env.RPCGenClient('src/rpcif.x')
SharedLibrary()
,
env.SharedLibrary()
Builds a shared library
(.so
on a POSIX system,
.dll
on Windows)
given one or more object files
or C, C++, D or Fortran source files.
If any source files are given,
then they will be automatically
compiled to object files.
The static library prefix and suffix (if any)
are automatically added to the target.
The target library file prefix
(specified by the $SHLIBPREFIX
construction variable;
by default, lib
on POSIX systems,
nothing on Windows systems)
and suffix
(specified by the $SHLIBSUFFIX
construction variable;
by default, .dll
on Windows systems,
.so
on POSIX systems)
are automatically added to the target if not already present.
Example:
env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o'])
On Windows systems, the
SharedLibrary
builder method will always build an import
(.lib
) library
in addition to the shared (.dll
) library,
adding a .lib
library with the same basename
if there is not already a .lib
file explicitly
listed in the targets.
On Cygwin systems, the
SharedLibrary
builder method will always build an import
(.dll.a
) library
in addition to the shared (.dll
) library,
adding a .dll.a
library with the same basename
if there is not already a .dll.a
file explicitly
listed in the targets.
Any object files listed in the
source
must have been built for a shared library
(that is, using the
SharedObject
builder method).
scons
will raise an error if there is any mismatch.
On some platforms, there is a distinction between a shared library
(loaded automatically by the system to resolve external references)
and a loadable module (explicitly loaded by user action).
For maximum portability, use the LoadableModule
builder for the latter.
When the $SHLIBVERSION
construction variable is defined a versioned
shared library is created. This modifies the $SHLINKFLAGS
as required,
adds the version number to the library name, and creates the symlinks that
are needed.
env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o'], SHLIBVERSION='1.5.2')
On a POSIX system, versions with a single token create exactly one symlink: libbar.so.6 would have symlinks libbar.so only. On a POSIX system, versions with two or more tokens create exactly two symlinks: libbar.so.2.3.1 would have symlinks libbar.so and libbar.so.2; on a Darwin (OSX) system the library would be libbar.2.3.1.dylib and the link would be libbar.dylib.
On Windows systems, specifying
register=1
will cause the .dll
to be
registered after it is built using REGSVR32.
The command that is run
("regsvr32" by default) is determined by $REGSVR
construction
variable, and the flags passed are determined by $REGSVRFLAGS
. By
default, $REGSVRFLAGS
includes the /s
option,
to prevent dialogs from popping
up and requiring user attention when it is run. If you change
$REGSVRFLAGS
, be sure to include the /s
option.
For example,
env.SharedLibrary(target = 'bar', source = ['bar.cxx', 'foo.obj'], register=1)
will register bar.dll
as a COM object
when it is done linking it.
SharedObject()
,
env.SharedObject()
Builds an object file for
inclusion in a shared library.
Source files must have one of the same set of extensions
specified above for the
StaticObject
builder method.
On some platforms building a shared object requires additional
compiler option
(e.g. -fPIC
for gcc)
in addition to those needed to build a
normal (static) object, but on some platforms there is no difference between a
shared object and a normal (static) one. When there is a difference, SCons
will only allow shared objects to be linked into a shared library, and will
use a different suffix for shared objects. On platforms where there is no
difference, SCons will allow both normal (static)
and shared objects to be linked into a
shared library, and will use the same suffix for shared and normal
(static) objects.
The target object file prefix
(specified by the $SHOBJPREFIX
construction variable;
by default, the same as $OBJPREFIX
)
and suffix
(specified by the $SHOBJSUFFIX
construction variable)
are automatically added to the target if not already present.
Examples:
env.SharedObject(target = 'ddd', source = 'ddd.c') env.SharedObject(target = 'eee.o', source = 'eee.cpp') env.SharedObject(target = 'fff.obj', source = 'fff.for')
Note that the source files will be scanned
according to the suffix mappings in the
SourceFileScanner
object.
See the section "Scanner Objects,"
below, for more information.
StaticLibrary()
,
env.StaticLibrary()
Builds a static library given one or more object files
or C, C++, D or Fortran source files.
If any source files are given,
then they will be automatically
compiled to object files.
The static library prefix and suffix (if any)
are automatically added to the target.
The target library file prefix
(specified by the $LIBPREFIX
construction variable;
by default, lib
on POSIX systems,
nothing on Windows systems)
and suffix
(specified by the $LIBSUFFIX
construction variable;
by default, .lib
on Windows systems,
.a
on POSIX systems)
are automatically added to the target if not already present.
Example:
env.StaticLibrary(target = 'bar', source = ['bar.c', 'foo.o'])
Any object files listed in the
source
must have been built for a static library
(that is, using the
StaticObject
builder method).
scons
will raise an error if there is any mismatch.
StaticObject()
,
env.StaticObject()
Builds a static object file from one or more C, C++, D, or Fortran source files. Source files must have one of the following extensions:
.asm assembly language file .ASM assembly language file .c C file .C Windows: C file POSIX: C++ file .cc C++ file .cpp C++ file .cxx C++ file .cxx C++ file .c++ C++ file .C++ C++ file .d D file .f Fortran file .F Windows: Fortran file POSIX: Fortran file + C pre-processor .for Fortran file .FOR Fortran file .fpp Fortran file + C pre-processor .FPP Fortran file + C pre-processor .m Object C file .mm Object C++ file .s assembly language file .S Windows: assembly language file ARM: CodeSourcery Sourcery Lite .sx assembly language file + C pre-processor POSIX: assembly language file + C pre-processor .spp assembly language file + C pre-processor .SPP assembly language file + C pre-processor
The target object file prefix
(specified by the $OBJPREFIX
construction variable; nothing by default)
and suffix
(specified by the $OBJSUFFIX
construction variable;
.obj
on Windows systems,
.o
on POSIX systems)
are automatically added to the target if not already present.
Examples:
env.StaticObject(target = 'aaa', source = 'aaa.c') env.StaticObject(target = 'bbb.o', source = 'bbb.c++') env.StaticObject(target = 'ccc.obj', source = 'ccc.f')
Note that the source files will be scanned
according to the suffix mappings in
SourceFileScanner
object.
See the section "Scanner Objects,"
below, for more information.
Substfile()
,
env.Substfile()
The Substfile
builder creates a single text file from another file or set of
files by concatenating them with $LINESEPARATOR
and replacing text
using the $SUBST_DICT
construction variable. Nested lists of source files
are flattened. See also Textfile
.
If a single source file is present with an .in
suffix,
the suffix is stripped and the remainder is used as the default target name.
The prefix and suffix specified by the $SUBSTFILEPREFIX
and $SUBSTFILESUFFIX
construction variables
(the null string by default in both cases)
are automatically added to the target if they are not already present.
If a construction variable named $SUBST_DICT
is present,
it may be either a Python dictionary or a sequence of (key,value) tuples.
If it is a dictionary it is converted into a list of tuples in an arbitrary order,
so if one key is a prefix of another key
or if one substitution could be further expanded by another subsitition,
it is unpredictable whether the expansion will occur.
Any occurrences of a key in the source are replaced by the corresponding value, which may be a Python callable function or a string. If the value is a callable, it is called with no arguments to get a string. Strings are subst-expanded and the result replaces the key.
env = Environment(tools = ['default', 'textfile']) env['prefix'] = '/usr/bin' script_dict = {'@prefix@': '/bin', '@exec_prefix@': '$prefix'} env.Substfile('script.in', SUBST_DICT = script_dict) conf_dict = {'%VERSION%': '1.2.3', '%BASE%': 'MyProg'} env.Substfile('config.h.in', conf_dict, SUBST_DICT = conf_dict) # UNPREDICTABLE - one key is a prefix of another bad_foo = {'$foo': '$foo', '$foobar': '$foobar'} env.Substfile('foo.in', SUBST_DICT = bad_foo) # PREDICTABLE - keys are applied longest first good_foo = [('$foobar', '$foobar'), ('$foo', '$foo')] env.Substfile('foo.in', SUBST_DICT = good_foo) # UNPREDICTABLE - one substitution could be futher expanded bad_bar = {'@bar@': '@soap@', '@soap@': 'lye'} env.Substfile('bar.in', SUBST_DICT = bad_bar) # PREDICTABLE - substitutions are expanded in order good_bar = (('@bar@', '@soap@'), ('@soap@', 'lye')) env.Substfile('bar.in', SUBST_DICT = good_bar) # the SUBST_DICT may be in common (and not an override) substutions = {} subst = Environment(tools = ['textfile'], SUBST_DICT = substitutions) substitutions['@foo@'] = 'foo' subst['SUBST_DICT']['@bar@'] = 'bar' subst.Substfile('pgm1.c', [Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm1.in" ]) subst.Substfile('pgm2.c', [Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm2.in" ])
Tar()
,
env.Tar()
Builds a tar archive of the specified files
and/or directories.
Unlike most builder methods,
the
Tar
builder method may be called multiple times
for a given target;
each additional call
adds to the list of entries
that will be built into the archive.
Any source directories will
be scanned for changes to
any on-disk files,
regardless of whether or not
scons
knows about them from other Builder or function calls.
env.Tar('src.tar', 'src') # Create the stuff.tar file. env.Tar('stuff', ['subdir1', 'subdir2']) # Also add "another" to the stuff.tar file. env.Tar('stuff', 'another') # Set TARFLAGS to create a gzip-filtered archive. env = Environment(TARFLAGS = '-c -z') env.Tar('foo.tar.gz', 'foo') # Also set the suffix to .tgz. env = Environment(TARFLAGS = '-c -z', TARSUFFIX = '.tgz') env.Tar('foo')
Textfile()
,
env.Textfile()
The Textfile
builder generates a single text file.
The source strings constitute the lines;
nested lists of sources are flattened.
$LINESEPARATOR
is used to separate the strings.
If present, the $SUBST_DICT
construction variable
is used to modify the strings before they are written;
see the Substfile
description for details.
The prefix and suffix specified by the $TEXTFILEPREFIX
and $TEXTFILESUFFIX
construction variables
(the null string and .txt
by default, respectively)
are automatically added to the target if they are not already present.
Examples:
# builds/writes foo.txt env.Textfile(target = 'foo.txt', source = ['Goethe', 42, 'Schiller']) # builds/writes bar.txt env.Textfile(target = 'bar', source = ['lalala', 'tanteratei'], LINESEPARATOR='|*') # nested lists are flattened automatically env.Textfile(target = 'blob', source = ['lalala', ['Goethe', 42 'Schiller'], 'tanteratei']) # files may be used as input by wraping them in File() env.Textfile(target = 'concat', # concatenate files with a marker between source = [File('concat1'), File('concat2')], LINESEPARATOR = '====================\n') Results are: foo.txt ....8<---- Goethe 42 Schiller ....8<---- (no linefeed at the end) bar.txt: ....8<---- lalala|*tanteratei ....8<---- (no linefeed at the end) blob.txt ....8<---- lalala Goethe 42 Schiller tanteratei ....8<---- (no linefeed at the end)
Translate()
,
env.Translate()
This pseudo-builder belongs to gettext
toolset. The builder extracts
internationalized messages from source files, updates POT
template (if necessary) and then updates PO
translations (if
necessary). If $POAUTOINIT
is set, missing PO
files
will be automatically created (i.e. without translator person intervention).
The variables $LINGUAS_FILE
and $POTDOMAIN
are taken into
acount too. All other construction variables used by POTUpdate
, and
POUpdate
work here too.
Example 1.
The simplest way is to specify input files and output languages inline in
a SCons script when invoking Translate
# SConscript in 'po/' directory env = Environment( tools = ["default", "gettext"] ) env['POAUTOINIT'] = 1 env.Translate(['en','pl'], ['../a.cpp','../b.cpp'])
Example 2.
If you wish, you may also stick to conventional style known from
autotools, i.e. using
POTFILES.in
and LINGUAS
files
# LINGUAS en pl #end
# POTFILES.in a.cpp b.cpp # end
# SConscript env = Environment( tools = ["default", "gettext"] ) env['POAUTOINIT'] = 1 env['XGETTEXTPATH'] = ['../'] env.Translate(LINGUAS_FILE = 1, XGETTEXTFROM = 'POTFILES.in')
The last approach is perhaps the recommended one. It allows easily split
internationalization/localization onto separate SCons scripts, where a script
in source tree is responsible for translations (from sources to
PO
files) and script(s) under variant directories are
responsible for compilation of PO
to MO
files to and for installation of MO
files. The "gluing
factor" synchronizing these two scripts is then the content of
LINGUAS
file. Note, that the updated
POT
and PO
files are usually going to be
committed back to the repository, so they must be updated within the source
directory (and not in variant directories). Additionaly, the file listing of
po/
directory contains LINGUAS
file,
so the source tree looks familiar to translators, and they may work with the
project in their usual way.
Example 3. Let's prepare a development tree as below
project/ + SConstruct + build/ + src/ + po/ + SConscript + SConscript.i18n + POTFILES.in + LINGUAS
with build
being variant directory. Write the top-level
SConstruct
script as follows
# SConstruct env = Environment( tools = ["default", "gettext"] ) VariantDir('build', 'src', duplicate = 0) env['POAUTOINIT'] = 1 SConscript('src/po/SConscript.i18n', exports = 'env') SConscript('build/po/SConscript', exports = 'env')
the src/po/SConscript.i18n
as
# src/po/SConscript.i18n Import('env') env.Translate(LINGUAS_FILE=1, XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../'])
and the src/po/SConscript
# src/po/SConscript Import('env') env.MOFiles(LINGUAS_FILE = 1)
Such setup produces POT
and PO
files
under source tree in src/po/
and binary
MO
files under variant tree in
build/po/
. This way the POT
and
PO
files are separated from other output files, which must
not be committed back to source repositories (e.g. MO
files).
In above example, the PO
files are not updated,
nor created automatically when you issue scons '.' command.
The files must be updated (created) by hand via scons
po-update and then MO
files can be compiled by
running scons '.'.
TypeLibrary()
,
env.TypeLibrary()
Builds a Windows type library (.tlb
)
file from an input IDL file (.idl
).
In addition, it will build the associated interface stub and
proxy source files,
naming them according to the base name of the .idl
file.
For example,
env.TypeLibrary(source="foo.idl")
Will create foo.tlb
,
foo.h
,
foo_i.c
,
foo_p.c
and
foo_data.c
files.
Uic()
,
env.Uic()
Builds a header file, an implementation file and a moc file from an ui file.
and returns the corresponding nodes in the above order.
This builder is only available after using the tool 'qt'. Note: you can
specify .ui
files directly as source
files to the Program
,
Library
and SharedLibrary
builders
without using this builder. Using this builder lets you override the standard
naming conventions (be careful: prefixes are always prepended to names of
built files; if you don't want prefixes, you may set them to ``).
See the $QTDIR
variable for more information.
Example:
env.Uic('foo.ui') # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc'] env.Uic(target = Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'), source = 'foo.ui') # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']
Zip()
,
env.Zip()
Builds a zip archive of the specified files
and/or directories.
Unlike most builder methods,
the
Zip
builder method may be called multiple times
for a given target;
each additional call
adds to the list of entries
that will be built into the archive.
Any source directories will
be scanned for changes to
any on-disk files,
regardless of whether or not
scons
knows about them from other Builder or function calls.
env.Zip('src.zip', 'src') # Create the stuff.zip file. env.Zip('stuff', ['subdir1', 'subdir2']) # Also add "another" to the stuff.tar file. env.Zip('stuff', 'another')
This appendix contains descriptions of all of the Tools modules that are available "out of the box" in this version of SCons.
Sets construction variables for the 386ASM assembler for the Phar Lap ETS embedded operating system.
Sets: $AS
, $ASCOM
, $ASFLAGS
, $ASPPCOM
, $ASPPFLAGS
.
Uses: $CC
, $CPPFLAGS
, $_CPPDEFFLAGS
, $_CPPINCFLAGS
.
Sets construction variables for the IMB xlc / Visual Age C++ compiler.
Sets: $CXX
, $CXXVERSION
, $SHCXX
, $SHOBJSUFFIX
.
Sets construction variables for the IBM xlc / Visual Age C compiler.
Sets: $CC
, $CCVERSION
, $SHCC
.
Sets construction variables for the IBM Visual Age f77 Fortran compiler.
Sets construction variables for the IBM Visual Age linker.
Sets: $LINKFLAGS
, $SHLIBSUFFIX
, $SHLINKFLAGS
.
Sets construction variables for the Apple linker (similar to the GNU linker).
Sets: $FRAMEWORKPATHPREFIX
, $LDMODULECOM
, $LDMODULEFLAGS
, $LDMODULEPREFIX
, $LDMODULESUFFIX
, $LINKCOM
, $SHLINKCOM
, $SHLINKFLAGS
, $_FRAMEWORKPATH
, $_FRAMEWORKS
.
Uses: $FRAMEWORKSFLAGS
.
Sets construction variables for the ar library archiver.
Sets: $AR
, $ARCOM
, $ARFLAGS
, $LIBPREFIX
, $LIBSUFFIX
, $RANLIB
, $RANLIBCOM
, $RANLIBFLAGS
.
Sets construction variables for the as assembler.
Sets: $AS
, $ASCOM
, $ASFLAGS
, $ASPPCOM
, $ASPPFLAGS
.
Uses: $CC
, $CPPFLAGS
, $_CPPDEFFLAGS
, $_CPPINCFLAGS
.
Sets construction variables for the bcc32 compiler.
Sets: $CC
, $CCCOM
, $CCFLAGS
, $CFILESUFFIX
, $CFLAGS
, $CPPDEFPREFIX
, $CPPDEFSUFFIX
, $INCPREFIX
, $INCSUFFIX
, $SHCC
, $SHCCCOM
, $SHCCFLAGS
, $SHCFLAGS
, $SHOBJSUFFIX
.
Uses: $_CPPDEFFLAGS
, $_CPPINCFLAGS
.
Sets construction variables for generic POSIX C copmilers.
Sets: $CC
, $CCCOM
, $CCFLAGS
, $CFILESUFFIX
, $CFLAGS
, $CPPDEFPREFIX
, $CPPDEFSUFFIX
, $FRAMEWORKPATH
, $FRAMEWORKS
, $INCPREFIX
, $INCSUFFIX
, $SHCC
, $SHCCCOM
, $SHCCFLAGS
, $SHCFLAGS
, $SHOBJSUFFIX
.
Uses: $PLATFORM
.
Set construction variables for the Clang C compiler.
Sets: $CC
, $CCVERSION
, $SHCCFLAGS
.
Set construction variables for the Clang C++ compiler.
Sets: $CXX
, $CXXVERSION
, $SHCXXFLAGS
, $SHOBJSUFFIX
, $STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME
.
Sets construction variables for the Compaq Visual Fortran compiler.
Sets: $FORTRAN
, $FORTRANCOM
, $FORTRANMODDIR
, $FORTRANMODDIRPREFIX
, $FORTRANMODDIRSUFFIX
, $FORTRANPPCOM
, $OBJSUFFIX
, $SHFORTRANCOM
, $SHFORTRANPPCOM
.
Uses: $CPPFLAGS
, $FORTRANFLAGS
, $SHFORTRANFLAGS
, $_CPPDEFFLAGS
, $_FORTRANINCFLAGS
, $_FORTRANMODFLAG
.
Sets construction variables for generic POSIX C++ compilers.
Sets: $CPPDEFPREFIX
, $CPPDEFSUFFIX
, $CXX
, $CXXCOM
, $CXXFILESUFFIX
, $CXXFLAGS
, $INCPREFIX
, $INCSUFFIX
, $OBJSUFFIX
, $SHCXX
, $SHCXXCOM
, $SHCXXFLAGS
, $SHOBJSUFFIX
.
Uses: $CXXCOMSTR
.
Set construction variables for cygwin linker/loader.
Sets: $IMPLIBPREFIX
, $IMPLIBSUFFIX
, $LDMODULEVERSIONFLAGS
, $LINKFLAGS
, $RPATHPREFIX
, $RPATHSUFFIX
, $SHLIBPREFIX
, $SHLIBSUFFIX
, $SHLIBVERSIONFLAGS
, $SHLINKCOM
, $SHLINKFLAGS
, $_LDMODULEVERSIONFLAGS
, $_SHLIBVERSIONFLAGS
.
Sets variables by calling a default list of Tool modules for the platform on which SCons is running.
Sets construction variables for D language compiler DMD.
Sets: $DC
, $DCOM
, $DDEBUG
, $DDEBUGPREFIX
, $DDEBUGSUFFIX
, $DFILESUFFIX
, $DFLAGPREFIX
, $DFLAGS
, $DFLAGSUFFIX
, $DINCPREFIX
, $DINCSUFFIX
, $DLIB
, $DLIBCOM
, $DLIBDIRPREFIX
, $DLIBDIRSUFFIX
, $DLIBFLAGPREFIX
, $DLIBFLAGSUFFIX
, $DLIBLINKPREFIX
, $DLIBLINKSUFFIX
, $DLINK
, $DLINKCOM
, $DLINKFLAGPREFIX
, $DLINKFLAGS
, $DLINKFLAGSUFFIX
, $DPATH
, $DRPATHPREFIX
, $DRPATHSUFFIX
, $DShLibSonameGenerator
, $DVERPREFIX
, $DVERSIONS
, $DVERSUFFIX
, $SHDC
, $SHDCOM
, $SHDLIBVERSION
, $SHDLIBVERSIONFLAGS
, $SHDLINK
, $SHDLINKCOM
, $SHDLINKFLAGS
.
This tool tries to make working with Docbook in SCons a little easier. It provides several toolchains for creating different output formats, like HTML or PDF. Contained in the package is a distribution of the Docbook XSL stylesheets as of version 1.76.1. As long as you don't specify your own stylesheets for customization, these official versions are picked as default...which should reduce the inevitable setup hassles for you.
Implicit dependencies to images and XIncludes are detected automatically
if you meet the HTML requirements. The additional
stylesheet utils/xmldepend.xsl
by Paul DuBois is used for this purpose.
Note, that there is no support for XML catalog resolving offered! This tool calls the XSLT processors and PDF renderers with the stylesheets you specified, that's it. The rest lies in your hands and you still have to know what you're doing when resolving names via a catalog.
For activating the tool "docbook", you have to add its name to the Environment constructor, like this
env = Environment(tools=['docbook'])
On its startup, the Docbook tool tries to find a required xsltproc
processor, and
a PDF renderer, e.g. fop
. So make sure that these are added to your system's environment
PATH
and can be called directly, without specifying their full path.
For the most basic processing of Docbook to HTML, you need to have installed
the Python lxml
binding to libxml2
, or
the direct Python bindings for libxml2/libxslt
, or
a standalone XSLT processor, currently detected are xsltproc
, saxon
, saxon-xslt
and xalan
.
Rendering to PDF requires you to have one of the applications
fop
or xep
installed.
Creating a HTML or PDF document is very simple and straightforward. Say
env = Environment(tools=['docbook']) env.DocbookHtml('manual.html', 'manual.xml') env.DocbookPdf('manual.pdf', 'manual.xml')
to get both outputs from your XML source manual.xml
. As a shortcut, you can
give the stem of the filenames alone, like this:
env = Environment(tools=['docbook']) env.DocbookHtml('manual') env.DocbookPdf('manual')
and get the same result. Target and source lists are also supported:
env = Environment(tools=['docbook']) env.DocbookHtml(['manual.html','reference.html'], ['manual.xml','reference.xml'])
or even
env = Environment(tools=['docbook']) env.DocbookHtml(['manual','reference'])
Whenever you leave out the list of sources, you may not specify a file extension! The Tool uses the given names as file stems, and adds the suffixes for target and source files accordingly.
The rules given above are valid for the Builders DocbookHtml
,
DocbookPdf
, DocbookEpub
, DocbookSlidesPdf
and DocbookXInclude
. For the
DocbookMan
transformation you
can specify a target name, but the actual output names are automatically
set from the refname
entries in your XML source.
The Builders DocbookHtmlChunked
, DocbookHtmlhelp
and
DocbookSlidesHtml
are special, in that:
they create a large set of files, where the exact names and their number depend on the content of the source file, and
the main target is always named index.html
, i.e. the output name for the
XSL transformation is not picked up by the stylesheets.
As a result, there is simply no use in specifying a target HTML name. So the basic syntax for these builders is always:
env = Environment(tools=['docbook']) env.DocbookHtmlhelp('manual')
If you want to use a specific XSL file, you can set the
additional xsl
parameter to your
Builder call as follows:
env.DocbookHtml('other.html', 'manual.xml', xsl='html.xsl')
Since this may get tedious if you always use the same local naming for your customized XSL files,
e.g. html.xsl
for HTML and pdf.xsl
for PDF output, a set of
variables for setting the default XSL name is provided. These are:
DOCBOOK_DEFAULT_XSL_HTML DOCBOOK_DEFAULT_XSL_HTMLCHUNKED DOCBOOK_DEFAULT_XSL_HTMLHELP DOCBOOK_DEFAULT_XSL_PDF DOCBOOK_DEFAULT_XSL_EPUB DOCBOOK_DEFAULT_XSL_MAN DOCBOOK_DEFAULT_XSL_SLIDESPDF DOCBOOK_DEFAULT_XSL_SLIDESHTML
and you can set them when constructing your environment:
env = Environment(tools=['docbook'], DOCBOOK_DEFAULT_XSL_HTML='html.xsl', DOCBOOK_DEFAULT_XSL_PDF='pdf.xsl') env.DocbookHtml('manual') # now uses html.xsl
Sets: $DOCBOOK_DEFAULT_XSL_EPUB
, $DOCBOOK_DEFAULT_XSL_HTML
, $DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
, $DOCBOOK_DEFAULT_XSL_HTMLHELP
, $DOCBOOK_DEFAULT_XSL_MAN
, $DOCBOOK_DEFAULT_XSL_PDF
, $DOCBOOK_DEFAULT_XSL_SLIDESHTML
, $DOCBOOK_DEFAULT_XSL_SLIDESPDF
, $DOCBOOK_FOP
, $DOCBOOK_FOPCOM
, $DOCBOOK_FOPFLAGS
, $DOCBOOK_XMLLINT
, $DOCBOOK_XMLLINTCOM
, $DOCBOOK_XMLLINTFLAGS
, $DOCBOOK_XSLTPROC
, $DOCBOOK_XSLTPROCCOM
, $DOCBOOK_XSLTPROCFLAGS
, $DOCBOOK_XSLTPROCPARAMS
.
Uses: $DOCBOOK_FOPCOMSTR
, $DOCBOOK_XMLLINTCOMSTR
, $DOCBOOK_XSLTPROCCOMSTR
.
Attaches the DVI
builder to the
construction environment.
Sets construction variables for the dvipdf utility.
Sets: $DVIPDF
, $DVIPDFCOM
, $DVIPDFFLAGS
.
Uses: $DVIPDFCOMSTR
.
Sets construction variables for the dvips utility.
Sets: $DVIPS
, $DVIPSFLAGS
, $PSCOM
, $PSPREFIX
, $PSSUFFIX
.
Uses: $PSCOMSTR
.
Set construction variables for generic POSIX Fortran 03 compilers.
Sets: $F03
, $F03COM
, $F03FLAGS
, $F03PPCOM
, $SHF03
, $SHF03COM
, $SHF03FLAGS
, $SHF03PPCOM
, $_F03INCFLAGS
.
Uses: $F03COMSTR
, $F03PPCOMSTR
, $SHF03COMSTR
, $SHF03PPCOMSTR
.
Set construction variables for generic POSIX Fortran 08 compilers.
Sets: $F08
, $F08COM
, $F08FLAGS
, $F08PPCOM
, $SHF08
, $SHF08COM
, $SHF08FLAGS
, $SHF08PPCOM
, $_F08INCFLAGS
.
Uses: $F08COMSTR
, $F08PPCOMSTR
, $SHF08COMSTR
, $SHF08PPCOMSTR
.
Set construction variables for generic POSIX Fortran 77 compilers.
Sets: $F77
, $F77COM
, $F77FILESUFFIXES
, $F77FLAGS
, $F77PPCOM
, $F77PPFILESUFFIXES
, $FORTRAN
, $FORTRANCOM
, $FORTRANFLAGS
, $SHF77
, $SHF77COM
, $SHF77FLAGS
, $SHF77PPCOM
, $SHFORTRAN
, $SHFORTRANCOM
, $SHFORTRANFLAGS
, $SHFORTRANPPCOM
, $_F77INCFLAGS
.
Uses: $F77COMSTR
, $F77PPCOMSTR
, $FORTRANCOMSTR
, $FORTRANPPCOMSTR
, $SHF77COMSTR
, $SHF77PPCOMSTR
, $SHFORTRANCOMSTR
, $SHFORTRANPPCOMSTR
.
Set construction variables for generic POSIX Fortran 90 compilers.
Sets: $F90
, $F90COM
, $F90FLAGS
, $F90PPCOM
, $SHF90
, $SHF90COM
, $SHF90FLAGS
, $SHF90PPCOM
, $_F90INCFLAGS
.
Uses: $F90COMSTR
, $F90PPCOMSTR
, $SHF90COMSTR
, $SHF90PPCOMSTR
.
Set construction variables for generic POSIX Fortran 95 compilers.
Sets: $F95
, $F95COM
, $F95FLAGS
, $F95PPCOM
, $SHF95
, $SHF95COM
, $SHF95FLAGS
, $SHF95PPCOM
, $_F95INCFLAGS
.
Uses: $F95COMSTR
, $F95PPCOMSTR
, $SHF95COMSTR
, $SHF95PPCOMSTR
.
Set construction variables for generic POSIX Fortran compilers.
Sets: $FORTRAN
, $FORTRANCOM
, $FORTRANFLAGS
, $SHFORTRAN
, $SHFORTRANCOM
, $SHFORTRANFLAGS
, $SHFORTRANPPCOM
.
Uses: $FORTRANCOMSTR
, $FORTRANPPCOMSTR
, $SHFORTRANCOMSTR
, $SHFORTRANPPCOMSTR
.
Set construction variables for the gXX C++ compiler.
Sets: $CXX
, $CXXVERSION
, $SHCXXFLAGS
, $SHOBJSUFFIX
.
Set construction variables for the g77 Fortran compiler.
Calls the f77
Tool module
to set variables.
Sets construction variables for the gas assembler.
Calls the as
module.
Sets: $AS
.
Set construction variables for the gcc C compiler.
Sets: $CC
, $CCVERSION
, $SHCCFLAGS
.
Sets construction variables for the D language compiler GDC.
Sets: $DC
, $DCOM
, $DDEBUG
, $DDEBUGPREFIX
, $DDEBUGSUFFIX
, $DFILESUFFIX
, $DFLAGPREFIX
, $DFLAGS
, $DFLAGSUFFIX
, $DINCPREFIX
, $DINCSUFFIX
, $DLIB
, $DLIBCOM
, $DLIBDIRPREFIX
, $DLIBDIRSUFFIX
, $DLIBFLAGPREFIX
, $DLIBFLAGSUFFIX
, $DLIBLINKPREFIX
, $DLIBLINKSUFFIX
, $DLINK
, $DLINKCOM
, $DLINKFLAGPREFIX
, $DLINKFLAGS
, $DLINKFLAGSUFFIX
, $DPATH
, $DRPATHPREFIX
, $DRPATHSUFFIX
, $DShLibSonameGenerator
, $DVERPREFIX
, $DVERSIONS
, $DVERSUFFIX
, $SHDC
, $SHDCOM
, $SHDLIBVERSION
, $SHDLIBVERSIONFLAGS
, $SHDLINK
, $SHDLINKCOM
, $SHDLINKFLAGS
.
This is actually a toolset, which supports internationalization and localization of software being constructed with SCons. The toolset loads following tools:
When you enable gettext
, it internally loads all abovementioned tools,
so you're encouraged to see their individual documentation.
Each of the above tools provides its own builder(s) which may be used to
perform particular activities related to software internationalization. You
may be however interested in top-level builder
Translate
described few paragraphs later.
To use gettext
tools add 'gettext'
tool to your
environment:
env = Environment( tools = ['default', 'gettext'] )
Sets construction variables for the GNU F95/F2003 GNU compiler.
Sets: $F77
, $F90
, $F95
, $FORTRAN
, $SHF77
, $SHF77FLAGS
, $SHF90
, $SHF90FLAGS
, $SHF95
, $SHF95FLAGS
, $SHFORTRAN
, $SHFORTRANFLAGS
.
Set construction variables for GNU linker/loader.
Sets: $LDMODULEVERSIONFLAGS
, $RPATHPREFIX
, $RPATHSUFFIX
, $SHLIBVERSIONFLAGS
, $SHLINKFLAGS
, $_LDMODULESONAME
, $_SHLIBSONAME
.
This Tool sets the required construction variables for working with
the Ghostscript command. It also registers an appropriate Action
with the PDF Builder (PDF
), such that the conversion from
PS/EPS to PDF happens automatically for the TeX/LaTeX toolchain.
Finally, it adds an explicit Ghostscript Builder (Gs
) to the
environment.
Uses: $GSCOMSTR
.
Set construction variables for the compilers aCC on HP/UX systems.
Set construction variables for the
aCC on HP/UX systems.
Calls the cXX
tool for additional variables.
Sets: $CXX
, $CXXVERSION
, $SHCXXFLAGS
.
Sets construction variables for the linker on HP/UX systems.
Sets: $LINKFLAGS
, $SHLIBSUFFIX
, $SHLINKFLAGS
.
Sets construction variables for the icc compiler on OS/2 systems.
Sets: $CC
, $CCCOM
, $CFILESUFFIX
, $CPPDEFPREFIX
, $CPPDEFSUFFIX
, $CXXCOM
, $CXXFILESUFFIX
, $INCPREFIX
, $INCSUFFIX
.
Uses: $CCFLAGS
, $CFLAGS
, $CPPFLAGS
, $_CPPDEFFLAGS
, $_CPPINCFLAGS
.
Sets construction variables for the Intel C/C++ compiler.
Calls the intelc
Tool module to set its variables.
Sets construction variables for the Intel Fortran compiler.
Sets: $FORTRAN
, $FORTRANCOM
, $FORTRANPPCOM
, $SHFORTRANCOM
, $SHFORTRANPPCOM
.
Uses: $CPPFLAGS
, $FORTRANFLAGS
, $_CPPDEFFLAGS
, $_FORTRANINCFLAGS
.
Sets construction variables for newer versions of the Intel Fortran compiler for Linux.
Sets: $F77
, $F90
, $F95
, $FORTRAN
, $SHF77
, $SHF77FLAGS
, $SHF90
, $SHF90FLAGS
, $SHF95
, $SHF95FLAGS
, $SHFORTRAN
, $SHFORTRANFLAGS
.
Sets construction variables for the ilink linker on OS/2 systems.
Sets: $LIBDIRPREFIX
, $LIBDIRSUFFIX
, $LIBLINKPREFIX
, $LIBLINKSUFFIX
, $LINK
, $LINKCOM
, $LINKFLAGS
.
Sets construction variables for the Borland ilink32 linker.
Sets: $LIBDIRPREFIX
, $LIBDIRSUFFIX
, $LIBLINKPREFIX
, $LIBLINKSUFFIX
, $LINK
, $LINKCOM
, $LINKFLAGS
.
Sets construction variables for file and directory installation.
Sets: $INSTALL
, $INSTALLSTR
.
Sets construction variables for the Intel C/C++ compiler
(Linux and Windows, version 7 and later).
Calls the gcc
or msvc
(on Linux and Windows, respectively)
to set underlying variables.
Sets: $AR
, $CC
, $CXX
, $INTEL_C_COMPILER_VERSION
, $LINK
.
Sets construction variables for the jar utility.
Sets: $JAR
, $JARCOM
, $JARFLAGS
, $JARSUFFIX
.
Uses: $JARCOMSTR
.
Sets construction variables for the javac compiler.
Sets: $JAVABOOTCLASSPATH
, $JAVAC
, $JAVACCOM
, $JAVACFLAGS
, $JAVACLASSPATH
, $JAVACLASSSUFFIX
, $JAVASOURCEPATH
, $JAVASUFFIX
.
Uses: $JAVACCOMSTR
.
Sets construction variables for the javah tool.
Sets: $JAVACLASSSUFFIX
, $JAVAH
, $JAVAHCOM
, $JAVAHFLAGS
.
Uses: $JAVACLASSPATH
, $JAVAHCOMSTR
.
Sets construction variables for the latex utility.
Sets: $LATEX
, $LATEXCOM
, $LATEXFLAGS
.
Uses: $LATEXCOMSTR
.
Sets construction variables for the D language compiler LDC2.
Sets: $DC
, $DCOM
, $DDEBUG
, $DDEBUGPREFIX
, $DDEBUGSUFFIX
, $DFILESUFFIX
, $DFLAGPREFIX
, $DFLAGS
, $DFLAGSUFFIX
, $DINCPREFIX
, $DINCSUFFIX
, $DLIB
, $DLIBCOM
, $DLIBDIRPREFIX
, $DLIBDIRSUFFIX
, $DLIBFLAGPREFIX
, $DLIBFLAGSUFFIX
, $DLIBLINKPREFIX
, $DLIBLINKSUFFIX
, $DLINK
, $DLINKCOM
, $DLINKFLAGPREFIX
, $DLINKFLAGS
, $DLINKFLAGSUFFIX
, $DPATH
, $DRPATHPREFIX
, $DRPATHSUFFIX
, $DShLibSonameGenerator
, $DVERPREFIX
, $DVERSIONS
, $DVERSUFFIX
, $SHDC
, $SHDCOM
, $SHDLIBVERSION
, $SHDLIBVERSIONFLAGS
, $SHDLINK
, $SHDLINKCOM
, $SHDLINKFLAGS
.
Sets construction variables for the lex lexical analyser.
Sets: $LEX
, $LEXCOM
, $LEXFLAGS
.
Uses: $LEXCOMSTR
.
Sets construction variables for generic POSIX linkers.
Sets: $LDMODULE
, $LDMODULECOM
, $LDMODULEFLAGS
, $LDMODULENOVERSIONSYMLINKS
, $LDMODULEPREFIX
, $LDMODULESUFFIX
, $LDMODULEVERSION
, $LDMODULEVERSIONFLAGS
, $LIBDIRPREFIX
, $LIBDIRSUFFIX
, $LIBLINKPREFIX
, $LIBLINKSUFFIX
, $LINK
, $LINKCOM
, $LINKFLAGS
, $SHLIBSUFFIX
, $SHLINK
, $SHLINKCOM
, $SHLINKFLAGS
, $__LDMODULEVERSIONFLAGS
, $__SHLIBVERSIONFLAGS
.
Uses: $LDMODULECOMSTR
, $LINKCOMSTR
, $SHLINKCOMSTR
.
Sets construction variables for the LinkLoc linker for the Phar Lap ETS embedded operating system.
Sets: $LIBDIRPREFIX
, $LIBDIRSUFFIX
, $LIBLINKPREFIX
, $LIBLINKSUFFIX
, $LINK
, $LINKCOM
, $LINKFLAGS
, $SHLINK
, $SHLINKCOM
, $SHLINKFLAGS
.
Uses: $LINKCOMSTR
, $SHLINKCOMSTR
.
Sets construction variables for the m4 macro processor.
Uses: $M4COMSTR
.
Sets construction variables for the Microsoft assembler.
Sets: $AS
, $ASCOM
, $ASFLAGS
, $ASPPCOM
, $ASPPFLAGS
.
Uses: $ASCOMSTR
, $ASPPCOMSTR
, $CPPFLAGS
, $_CPPDEFFLAGS
, $_CPPINCFLAGS
.
Sets construction variables for the Microsoft IDL compiler.
Sets: $MIDL
, $MIDLCOM
, $MIDLFLAGS
.
Uses: $MIDLCOMSTR
.
Sets construction variables for MinGW (Minimal Gnu on Windows).
Sets: $AS
, $CC
, $CXX
, $LDMODULECOM
, $LIBPREFIX
, $LIBSUFFIX
, $OBJSUFFIX
, $RC
, $RCCOM
, $RCFLAGS
, $RCINCFLAGS
, $RCINCPREFIX
, $RCINCSUFFIX
, $SHCCFLAGS
, $SHCXXFLAGS
, $SHLINKCOM
, $SHLINKFLAGS
, $SHOBJSUFFIX
, $WINDOWSDEFPREFIX
, $WINDOWSDEFSUFFIX
.
Uses: $RCCOMSTR
, $SHLINKCOMSTR
.
This scons tool is a part of scons gettext
toolset. It provides scons
interface to msgfmt(1) command, which generates binary
message catalog (MO
) from a textual translation description
(PO
).
Sets: $MOSUFFIX
, $MSGFMT
, $MSGFMTCOM
, $MSGFMTCOMSTR
, $MSGFMTFLAGS
, $POSUFFIX
.
Uses: $LINGUAS_FILE
.
This scons tool is a part of scons gettext
toolset. It provides
scons interface to msginit(1) program, which creates new
PO
file, initializing the meta information with values from
user's environment (or options).
Sets: $MSGINIT
, $MSGINITCOM
, $MSGINITCOMSTR
, $MSGINITFLAGS
, $POAUTOINIT
, $POCREATE_ALIAS
, $POSUFFIX
, $POTSUFFIX
, $_MSGINITLOCALE
.
Uses: $LINGUAS_FILE
, $POAUTOINIT
, $POTDOMAIN
.
This scons tool is a part of scons gettext
toolset. It provides
scons interface to msgmerge(1) command, which merges two
Uniform style .po
files together.
Sets: $MSGMERGE
, $MSGMERGECOM
, $MSGMERGECOMSTR
, $MSGMERGEFLAGS
, $POSUFFIX
, $POTSUFFIX
, $POUPDATE_ALIAS
.
Uses: $LINGUAS_FILE
, $POAUTOINIT
, $POTDOMAIN
.
Sets construction variables for the Microsoft mslib library archiver.
Sets: $AR
, $ARCOM
, $ARFLAGS
, $LIBPREFIX
, $LIBSUFFIX
.
Uses: $ARCOMSTR
.
Sets construction variables for the Microsoft linker.
Sets: $LDMODULE
, $LDMODULECOM
, $LDMODULEFLAGS
, $LDMODULEPREFIX
, $LDMODULESUFFIX
, $LIBDIRPREFIX
, $LIBDIRSUFFIX
, $LIBLINKPREFIX
, $LIBLINKSUFFIX
, $LINK
, $LINKCOM
, $LINKFLAGS
, $REGSVR
, $REGSVRCOM
, $REGSVRFLAGS
, $SHLINK
, $SHLINKCOM
, $SHLINKFLAGS
, $WIN32DEFPREFIX
, $WIN32DEFSUFFIX
, $WIN32EXPPREFIX
, $WIN32EXPSUFFIX
, $WINDOWSDEFPREFIX
, $WINDOWSDEFSUFFIX
, $WINDOWSEXPPREFIX
, $WINDOWSEXPSUFFIX
, $WINDOWSPROGMANIFESTPREFIX
, $WINDOWSPROGMANIFESTSUFFIX
, $WINDOWSSHLIBMANIFESTPREFIX
, $WINDOWSSHLIBMANIFESTSUFFIX
, $WINDOWS_INSERT_DEF
.
Uses: $LDMODULECOMSTR
, $LINKCOMSTR
, $REGSVRCOMSTR
, $SHLINKCOMSTR
.
Sets variables for Microsoft Platform SDK and/or Windows SDK.
Note that unlike most other Tool modules,
mssdk does not set construction variables,
but sets the environment variables
in the environment SCons uses to execute
the Microsoft toolchain:
%INCLUDE%
,
%LIB%
,
%LIBPATH%
and
%PATH%
.
Uses: $MSSDK_DIR
, $MSSDK_VERSION
, $MSVS_VERSION
.
Sets construction variables for the Microsoft Visual C/C++ compiler.
Sets: $BUILDERS
, $CC
, $CCCOM
, $CCFLAGS
, $CCPCHFLAGS
, $CCPDBFLAGS
, $CFILESUFFIX
, $CFLAGS
, $CPPDEFPREFIX
, $CPPDEFSUFFIX
, $CXX
, $CXXCOM
, $CXXFILESUFFIX
, $CXXFLAGS
, $INCPREFIX
, $INCSUFFIX
, $OBJPREFIX
, $OBJSUFFIX
, $PCHCOM
, $PCHPDBFLAGS
, $RC
, $RCCOM
, $RCFLAGS
, $SHCC
, $SHCCCOM
, $SHCCFLAGS
, $SHCFLAGS
, $SHCXX
, $SHCXXCOM
, $SHCXXFLAGS
, $SHOBJPREFIX
, $SHOBJSUFFIX
.
Uses: $CCCOMSTR
, $CXXCOMSTR
, $PCH
, $PCHSTOP
, $PDB
, $SHCCCOMSTR
, $SHCXXCOMSTR
.
Sets construction variables for Microsoft Visual Studio.
Sets: $MSVSBUILDCOM
, $MSVSCLEANCOM
, $MSVSENCODING
, $MSVSPROJECTCOM
, $MSVSREBUILDCOM
, $MSVSSCONS
, $MSVSSCONSCOM
, $MSVSSCONSCRIPT
, $MSVSSCONSFLAGS
, $MSVSSOLUTIONCOM
.
Sets construction variables for the Metrowerks CodeWarrior compiler.
Sets: $CC
, $CCCOM
, $CFILESUFFIX
, $CPPDEFPREFIX
, $CPPDEFSUFFIX
, $CXX
, $CXXCOM
, $CXXFILESUFFIX
, $INCPREFIX
, $INCSUFFIX
, $MWCW_VERSION
, $MWCW_VERSIONS
, $SHCC
, $SHCCCOM
, $SHCCFLAGS
, $SHCFLAGS
, $SHCXX
, $SHCXXCOM
, $SHCXXFLAGS
.
Uses: $CCCOMSTR
, $CXXCOMSTR
, $SHCCCOMSTR
, $SHCXXCOMSTR
.
Sets construction variables for the Metrowerks CodeWarrior linker.
Sets: $AR
, $ARCOM
, $LIBDIRPREFIX
, $LIBDIRSUFFIX
, $LIBLINKPREFIX
, $LIBLINKSUFFIX
, $LINK
, $LINKCOM
, $SHLINK
, $SHLINKCOM
, $SHLINKFLAGS
.
Sets construction variables for the nasm Netwide Assembler.
Sets: $AS
, $ASCOM
, $ASFLAGS
, $ASPPCOM
, $ASPPFLAGS
.
Uses: $ASCOMSTR
, $ASPPCOMSTR
.
A framework for building binary and source packages.
Sets construction variables for the Package
Builder.
Sets construction variables for the Portable Document Format builder.
Sets: $PDFPREFIX
, $PDFSUFFIX
.
Sets construction variables for the pdflatex utility.
Sets: $LATEXRETRIES
, $PDFLATEX
, $PDFLATEXCOM
, $PDFLATEXFLAGS
.
Uses: $PDFLATEXCOMSTR
.
Sets construction variables for the pdftex utility.
Sets: $LATEXRETRIES
, $PDFLATEX
, $PDFLATEXCOM
, $PDFLATEXFLAGS
, $PDFTEX
, $PDFTEXCOM
, $PDFTEXFLAGS
.
Uses: $PDFLATEXCOMSTR
, $PDFTEXCOMSTR
.
Sets construction variables for building Qt applications.
Sets: $QTDIR
, $QT_AUTOSCAN
, $QT_BINPATH
, $QT_CPPPATH
, $QT_LIB
, $QT_LIBPATH
, $QT_MOC
, $QT_MOCCXXPREFIX
, $QT_MOCCXXSUFFIX
, $QT_MOCFROMCXXCOM
, $QT_MOCFROMCXXFLAGS
, $QT_MOCFROMHCOM
, $QT_MOCFROMHFLAGS
, $QT_MOCHPREFIX
, $QT_MOCHSUFFIX
, $QT_UIC
, $QT_UICCOM
, $QT_UICDECLFLAGS
, $QT_UICDECLPREFIX
, $QT_UICDECLSUFFIX
, $QT_UICIMPLFLAGS
, $QT_UICIMPLPREFIX
, $QT_UICIMPLSUFFIX
, $QT_UISUFFIX
.
Sets construction variables for the rmic utility.
Sets: $JAVACLASSSUFFIX
, $RMIC
, $RMICCOM
, $RMICFLAGS
.
Uses: $RMICCOMSTR
.
Sets construction variables for building with RPCGEN.
Sets: $RPCGEN
, $RPCGENCLIENTFLAGS
, $RPCGENFLAGS
, $RPCGENHEADERFLAGS
, $RPCGENSERVICEFLAGS
, $RPCGENXDRFLAGS
.
Sets construction variables for the SGI library archiver.
Sets: $AR
, $ARCOMSTR
, $ARFLAGS
, $LIBPREFIX
, $LIBSUFFIX
, $SHLINK
, $SHLINKFLAGS
.
Uses: $ARCOMSTR
, $SHLINKCOMSTR
.
Sets construction variables for the SGI C++ compiler.
Sets: $CXX
, $CXXFLAGS
, $SHCXX
, $SHOBJSUFFIX
.
Sets construction variables for the SGI C compiler.
Sets: $CXX
, $SHOBJSUFFIX
.
Sets construction variables for the SGI linker.
Sets: $LINK
, $RPATHPREFIX
, $RPATHSUFFIX
, $SHLINKFLAGS
.
Sets construction variables for the Sun library archiver.
Sets: $AR
, $ARCOM
, $ARFLAGS
, $LIBPREFIX
, $LIBSUFFIX
.
Uses: $ARCOMSTR
.
Sets construction variables for the Sun C++ compiler.
Sets: $CXX
, $CXXVERSION
, $SHCXX
, $SHCXXFLAGS
, $SHOBJPREFIX
, $SHOBJSUFFIX
.
Sets construction variables for the Sun C compiler.
Sets: $CXX
, $SHCCFLAGS
, $SHOBJPREFIX
, $SHOBJSUFFIX
.
Set construction variables for the Sun f77 Fortran compiler.
Sets: $F77
, $FORTRAN
, $SHF77
, $SHF77FLAGS
, $SHFORTRAN
, $SHFORTRANFLAGS
.
Set construction variables for the Sun f90 Fortran compiler.
Sets: $F90
, $FORTRAN
, $SHF90
, $SHF90FLAGS
, $SHFORTRAN
, $SHFORTRANFLAGS
.
Set construction variables for the Sun f95 Fortran compiler.
Sets: $F95
, $FORTRAN
, $SHF95
, $SHF95FLAGS
, $SHFORTRAN
, $SHFORTRANFLAGS
.
Sets construction variables for the Sun linker.
Sets: $RPATHPREFIX
, $RPATHSUFFIX
, $SHLINKFLAGS
.
Sets construction variables for the SWIG interface generator.
Sets: $SWIG
, $SWIGCFILESUFFIX
, $SWIGCOM
, $SWIGCXXFILESUFFIX
, $SWIGDIRECTORSUFFIX
, $SWIGFLAGS
, $SWIGINCPREFIX
, $SWIGINCSUFFIX
, $SWIGPATH
, $SWIGVERSION
, $_SWIGINCFLAGS
.
Uses: $SWIGCOMSTR
.
Sets construction variables for the tar archiver.
Sets: $TAR
, $TARCOM
, $TARFLAGS
, $TARSUFFIX
.
Uses: $TARCOMSTR
.
Sets construction variables for the TeX formatter and typesetter.
Sets: $BIBTEX
, $BIBTEXCOM
, $BIBTEXFLAGS
, $LATEX
, $LATEXCOM
, $LATEXFLAGS
, $MAKEINDEX
, $MAKEINDEXCOM
, $MAKEINDEXFLAGS
, $TEX
, $TEXCOM
, $TEXFLAGS
.
Uses: $BIBTEXCOMSTR
, $LATEXCOMSTR
, $MAKEINDEXCOMSTR
, $TEXCOMSTR
.
Set construction variables for the Textfile
and Substfile
builders.
Sets: $LINESEPARATOR
, $SUBSTFILEPREFIX
, $SUBSTFILESUFFIX
, $TEXTFILEPREFIX
, $TEXTFILESUFFIX
.
Uses: $SUBST_DICT
.
Sets construction variables for the Borlan tib library archiver.
Sets: $AR
, $ARCOM
, $ARFLAGS
, $LIBPREFIX
, $LIBSUFFIX
.
Uses: $ARCOMSTR
.
This scons tool is a part of scons gettext
toolset. It provides
scons interface to xgettext(1)
program, which extracts internationalized messages from source code. The tool
provides POTUpdate
builder to make PO
Template files.
Sets: $POTSUFFIX
, $POTUPDATE_ALIAS
, $XGETTEXTCOM
, $XGETTEXTCOMSTR
, $XGETTEXTFLAGS
, $XGETTEXTFROM
, $XGETTEXTFROMPREFIX
, $XGETTEXTFROMSUFFIX
, $XGETTEXTPATH
, $XGETTEXTPATHPREFIX
, $XGETTEXTPATHSUFFIX
, $_XGETTEXTDOMAIN
, $_XGETTEXTFROMFLAGS
, $_XGETTEXTPATHFLAGS
.
Uses: $POTDOMAIN
.
Sets construction variables for the yacc parse generator.
Sets: $YACC
, $YACCCOM
, $YACCFLAGS
, $YACCHFILESUFFIX
, $YACCHXXFILESUFFIX
, $YACCVCGFILESUFFIX
.
Uses: $YACCCOMSTR
.
Sets construction variables for the zip archiver.
Sets: $ZIP
, $ZIPCOM
, $ZIPCOMPRESSION
, $ZIPFLAGS
, $ZIPSUFFIX
.
Uses: $ZIPCOMSTR
.
This appendix contains descriptions of all of the function and construction environment methods in this version of SCons
Action(action, [cmd/str/fun, [var, ...]] [option=value, ...])
,
env.Action(action, [cmd/str/fun, [var, ...]] [option=value, ...])
Creates an Action object for
the specified
action
.
See the section "Action Objects,"
below, for a complete explanation of the arguments and behavior.
Note that the
env.Action
()
form of the invocation will expand
construction variables in any argument strings,
including the
action
argument, at the time it is called
using the construction variables in the
env
construction environment through which
env.Action
()
was called.
The
Action
()
form delays all variable expansion
until the Action object is actually used.
AddMethod(object, function, [name])
,
env.AddMethod(function, [name])
When called with the
AddMethod
()
form,
adds the specified
function
to the specified
object
as the specified method
name
.
When called with the
env.AddMethod
()
form,
adds the specified
function
to the construction environment
env
as the specified method
name
.
In both cases, if
name
is omitted or
None
,
the name of the
specified
function
itself is used for the method name.
Examples:
# Note that the first argument to the function to # be attached as a method must be the object through # which the method will be called; the Python # convention is to call it 'self'. def my_method(self, arg): print("my_method() got", arg) # Use the global AddMethod() function to add a method # to the Environment class. This AddMethod(Environment, my_method) env = Environment() env.my_method('arg') # Add the function as a method, using the function # name for the method call. env = Environment() env.AddMethod(my_method, 'other_method_name') env.other_method_name('another arg')
AddOption(arguments)
This function adds a new command-line option to be recognized.
The specified
arguments
are the same as supported by the standard Python
optparse.add_option
()
method (with a few additional capabilities noted below);
see the documentation for
optparse
for a thorough discussion of its option-processing capabities.
In addition to the arguments and values supported by the
optparse.add_option
()
method,
the SCons
AddOption
function allows you to set the
nargs
keyword value to
'?'
(a string with just the question mark)
to indicate that the specified long option(s) take(s) an
optional
argument.
When
nargs = '?'
is passed to the
AddOption
function, the
const
keyword argument
may be used to supply the "default"
value that should be used when the
option is specified on the command line
without an explicit argument.
If no
default=
keyword argument is supplied when calling
AddOption
,
the option will have a default value of
None
.
Once a new command-line option has been added with
AddOption
,
the option value may be accessed using
GetOption
or
env.GetOption
().
The value may also be set, using
SetOption
or
env.SetOption
(),
if conditions in a
SConscript
require overriding any default value.
Note, however, that a
value specified on the command line will
always
override a value set by any SConscript file.
Any specified
help=
strings for the new option(s)
will be displayed by the
-H
or
-h
options
(the latter only if no other help text is
specified in the SConscript files).
The help text for the local options specified by
AddOption
will appear below the SCons options themselves,
under a separate
Local Options
heading.
The options will appear in the help text
in the order in which the
AddOption
calls occur.
Example:
AddOption('--prefix', dest='prefix', nargs=1, type='string', action='store', metavar='DIR', help='installation prefix') env = Environment(PREFIX = GetOption('prefix'))
AddPostAction(target, action)
,
env.AddPostAction(target, action)
Arranges for the specified
action
to be performed
after the specified
target
has been built.
The specified action(s) may be
an Action object, or anything that
can be converted into an Action object
(see below).
When multiple targets are supplied, the action may be called multiple times, once after each action that generates one or more targets in the list.
AddPreAction(target, action)
,
env.AddPreAction(target, action)
Arranges for the specified
action
to be performed
before the specified
target
is built.
The specified action(s) may be
an Action object, or anything that
can be converted into an Action object
(see below).
When multiple targets are specified, the action(s) may be called multiple times, once before each action that generates one or more targets in the list.
Note that if any of the targets are built in multiple steps,
the action will be invoked just
before the "final" action that specifically
generates the specified target(s).
For example, when building an executable program
from a specified source
.c
file via an intermediate object file:
foo = Program('foo.c') AddPreAction(foo, 'pre_action')
The specified
pre_action
would be executed before
scons
calls the link command that actually
generates the executable program binary
foo
,
not before compiling the
foo.c
file into an object file.
Alias(alias, [targets, [action]])
,
env.Alias(alias, [targets, [action]])
Creates one or more phony targets that
expand to one or more other targets.
An optional
action
(command)
or list of actions
can be specified that will be executed
whenever the any of the alias targets are out-of-date.
Returns the Node object representing the alias,
which exists outside of any file system.
This Node object, or the alias name,
may be used as a dependency of any other target,
including another alias.
Alias
can be called multiple times for the same
alias to add additional targets to the alias,
or additional actions to the list for this alias.
Examples:
Alias('install') Alias('install', '/usr/bin') Alias(['install', 'install-lib'], '/usr/local/lib') env.Alias('install', ['/usr/local/bin', '/usr/local/lib']) env.Alias('install', ['/usr/local/man']) env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")
AllowSubstExceptions([exception, ...])
Specifies the exceptions that will be allowed
when expanding construction variables.
By default,
any construction variable expansions that generate a
NameError
or
IndexError
exception will expand to a
''
(a null string) and not cause scons to fail.
All exceptions not in the specified list
will generate an error message
and terminate processing.
If
AllowSubstExceptions
is called multiple times,
each call completely overwrites the previous list
of allowed exceptions.
Example:
# Requires that all construction variable names exist. # (You may wish to do this if you want to enforce strictly # that all construction variables must be defined before use.) AllowSubstExceptions() # Also allow a string containing a zero-division expansion # like '${1 / 0}' to evalute to ''. AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)
AlwaysBuild(target, ...)
,
env.AlwaysBuild(target, ...)
Marks each given
target
so that it is always assumed to be out of date,
and will always be rebuilt if needed.
Note, however, that
AlwaysBuild
does not add its target(s) to the default target list,
so the targets will only be built
if they are specified on the command line,
or are a dependent of a target specified on the command line--but
they will
always
be built if so specified.
Multiple targets can be passed in to a single call to
AlwaysBuild
.
env.Append(key=val, [...])
Appends the specified keyword arguments to the end of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the values of the construction variable and the keyword argument are the same type, then the two values will be simply added together. Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. (See also the Prepend method, below.)
Example:
env.Append(CCFLAGS = ' -g', FOO = ['foo.yyy'])
env.AppendENVPath(name, newpath, [envname, sep, delete_existing])
This appends new path elements to the given path in the
specified external environment
(ENV
by default).
This will only add
any particular path once (leaving the last one it encounters and
ignoring the rest, to preserve path order),
and to help assure this,
will normalize all paths (using
os.path.normpath
and
os.path.normcase
).
This can also handle the
case where the given old path variable is a list instead of a
string, in which case a list will be returned instead of a string.
If
delete_existing
is 0, then adding a path that already exists
will not move it to the end; it will stay where it is in the list.
Example:
print 'before:',env['ENV']['INCLUDE'] include_path = '/foo/bar:/foo' env.AppendENVPath('INCLUDE', include_path) print 'after:',env['ENV']['INCLUDE'] yields: before: /foo:/biz after: /biz:/foo/bar:/foo
env.AppendUnique(key=val, [...], delete_existing=0)
Appends the specified keyword arguments to the end of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the construction variable being appended to is a list, then any value(s) that already exist in the construction variable will not be added again to the list. However, if delete_existing is 1, existing matching values are removed first, so existing values in the arg list move to the end of the list.
Example:
env.AppendUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])
BuildDir(build_dir, src_dir, [duplicate])
,
env.BuildDir(build_dir, src_dir, [duplicate])
Deprecated synonyms for
VariantDir
and
env.VariantDir
().
The
build_dir
argument becomes the
variant_dir
argument of
VariantDir
or
env.VariantDir
().
Builder(action, [arguments])
,
env.Builder(action, [arguments])
Creates a Builder object for
the specified
action
.
See the section "Builder Objects,"
below, for a complete explanation of the arguments and behavior.
Note that the
env.Builder
()
form of the invocation will expand
construction variables in any arguments strings,
including the
action
argument,
at the time it is called
using the construction variables in the
env
construction environment through which
env.Builder
()
was called.
The
Builder
form delays all variable expansion
until after the Builder object is actually called.
CacheDir(cache_dir)
,
env.CacheDir(cache_dir)
Specifies that
scons
will maintain a cache of derived files in
cache_dir
.
The derived files in the cache will be shared
among all the builds using the same
CacheDir
call.
Specifying a
cache_dir
of
None
disables derived file caching.
Calling
env.CacheDir
()
will only affect targets built
through the specified construction environment.
Calling
CacheDir
sets a global default
that will be used by all targets built
through construction environments
that do
not
have an
env.CacheDir
()
specified.
When a
CacheDir
()
is being used and
scons
finds a derived file that needs to be rebuilt,
it will first look in the cache to see if a
derived file has already been built
from identical input files and an identical build action
(as incorporated into the MD5 build signature).
If so,
scons
will retrieve the file from the cache.
If the derived file is not present in the cache,
scons
will rebuild it and
then place a copy of the built file in the cache
(identified by its MD5 build signature),
so that it may be retrieved by other
builds that need to build the same derived file
from identical inputs.
Use of a specified
CacheDir
may be disabled for any invocation
by using the
--cache-disable
option.
If the
--cache-force
option is used,
scons
will place a copy of
all
derived files in the cache,
even if they already existed
and were not built by this invocation.
This is useful to populate a cache
the first time
CacheDir
is added to a build,
or after using the
--cache-disable
option.
When using
CacheDir
,
scons
will report,
"Retrieved `file' from cache,"
unless the
--cache-show
option is being used.
When the
--cache-show
option is used,
scons
will print the action that
would
have been used to build the file,
without any indication that
the file was actually retrieved from the cache.
This is useful to generate build logs
that are equivalent regardless of whether
a given derived file has been built in-place
or retrieved from the cache.
The
NoCache
method can be used to disable caching of specific files. This can be
useful if inputs and/or outputs of some tool are impossible to
predict or prohibitively large.
Clean(targets, files_or_dirs)
,
env.Clean(targets, files_or_dirs)
This specifies a list of files or directories which should be removed
whenever the targets are specified with the
-c
command line option.
The specified targets may be a list
or an individual target.
Multiple calls to
Clean
are legal,
and create new targets or add files and directories to the
clean list for the specified targets.
Multiple files or directories should be specified
either as separate arguments to the
Clean
method, or as a list.
Clean
will also accept the return value of any of the construction environment
Builder methods.
Examples:
The related
NoClean
function overrides calling
Clean
for the same target,
and any targets passed to both functions will
not
be removed by the
-c
option.
Examples:
Clean('foo', ['bar', 'baz']) Clean('dist', env.Program('hello', 'hello.c')) Clean(['foo', 'bar'], 'something_else_to_clean')
In this example, installing the project creates a subdirectory for the documentation. This statement causes the subdirectory to be removed if the project is deinstalled.
Clean(docdir, os.path.join(docdir, projectname))
env.Clone([key=val, ...])
Returns a separate copy of a construction environment. If there are any keyword arguments specified, they are added to the returned copy, overwriting any existing values for the keywords.
Example:
env2 = env.Clone() env3 = env.Clone(CCFLAGS = '-g')
Additionally, a list of tools and a toolpath may be specified, as in the Environment constructor:
def MyTool(env): env['FOO'] = 'bar' env4 = env.Clone(tools = ['msvc', MyTool])
The
parse_flags
keyword argument is also recognized:
# create an environment for compiling programs that use wxWidgets wx_env = env.Clone(parse_flags = '!wx-config --cflags --cxxflags')
Command(target, source, action, [key=val, ...])
,
env.Command(target, source, action, [key=val, ...])
Executes a specific action (or list of actions) to build a target file or files. This is more convenient than defining a separate Builder object for a single special-case build.
As a special case, the
source_scanner
keyword argument can
be used to specify
a Scanner object
that will be used to scan the sources.
(The global
DirScanner
object can be used
if any of the sources will be directories
that must be scanned on-disk for
changes to files that aren't
already specified in other Builder of function calls.)
Any other keyword arguments specified override any same-named existing construction variables.
An action can be an external command,
specified as a string,
or a callable Python object;
see "Action Objects," below,
for more complete information.
Also note that a string specifying an external command
may be preceded by an
@
(at-sign)
to suppress printing the command in question,
or by a
-
(hyphen)
to ignore the exit status of the external command.
Examples:
env.Command('foo.out', 'foo.in', "$FOO_BUILD < $SOURCES > $TARGET") env.Command('bar.out', 'bar.in', ["rm -f $TARGET", "$BAR_BUILD < $SOURCES > $TARGET"], ENV = {'PATH' : '/usr/local/bin/'}) def rename(env, target, source): import os os.rename('.tmp', str(target[0])) env.Command('baz.out', 'baz.in', ["$BAZ_BUILD < $SOURCES > .tmp", rename ])
Note that the
Command
function will usually assume, by default,
that the specified targets and/or sources are Files,
if no other part of the configuration
identifies what type of entry it is.
If necessary, you can explicitly specify
that targets or source nodes should
be treated as directoriese
by using the
Dir
or
env.Dir
()
functions.
Examples:
env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET') env['DISTDIR'] = 'destination/directory' env.Command(env.Dir('$DISTDIR')), None, make_distdir)
(Also note that SCons will usually automatically create any directory necessary to hold a target file, so you normally don't need to create directories by hand.)
Configure(env, [custom_tests, conf_dir, log_file, config_h])
,
env.Configure([custom_tests, conf_dir, log_file, config_h])
Creates a Configure object for integrated functionality similar to GNU autoconf. See the section "Configure Contexts," below, for a complete explanation of the arguments and behavior.
env.Copy([key=val, ...])
A now-deprecated synonym for
env.Clone
().
Decider(function)
,
env.Decider(function)
Specifies that all up-to-date decisions for
targets built through this construction environment
will be handled by the specified
function
.
The
function
can be one of the following strings
that specify the type of decision function
to be performed:
timestamp-newer
Specifies that a target shall be considered out of date and rebuilt
if the dependency's timestamp is newer than the target file's timestamp.
This is the behavior of the classic Make utility,
and
make
can be used a synonym for
timestamp-newer
.
timestamp-match
Specifies that a target shall be considered out of date and rebuilt if the dependency's timestamp is different than the timestamp recorded the last time the target was built. This provides behavior very similar to the classic Make utility (in particular, files are not opened up so that their contents can be checksummed) except that the target will also be rebuilt if a dependency file has been restored to a version with an earlier timestamp, such as can happen when restoring files from backup archives.
MD5
Specifies that a target shall be considered out of date and rebuilt
if the dependency's content has changed since the last time
the target was built,
as determined be performing an MD5 checksum
on the dependency's contents
and comparing it to the checksum recorded the
last time the target was built.
content
can be used as a synonym for
MD5
.
MD5-timestamp
Specifies that a target shall be considered out of date and rebuilt
if the dependency's content has changed since the last time
the target was built,
except that dependencies with a timestamp that matches
the last time the target was rebuilt will be
assumed to be up-to-date and
not
rebuilt.
This provides behavior very similar
to the
MD5
behavior of always checksumming file contents,
with an optimization of not checking
the contents of files whose timestamps haven't changed.
The drawback is that SCons will
not
detect if a file's content has changed
but its timestamp is the same,
as might happen in an automated script
that runs a build,
updates a file,
and runs the build again,
all within a single second.
Examples:
# Use exact timestamp matches by default. Decider('timestamp-match') # Use MD5 content signatures for any targets built # with the attached construction environment. env.Decider('content')
In addition to the above already-available functions,
the
function
argument may be an actual Python function
that takes the following three arguments:
dependency
The Node (file) which
should cause the
target
to be rebuilt
if it has "changed" since the last tme
target
was built.
target
The Node (file) being built.
In the normal case,
this is what should get rebuilt
if the
dependency
has "changed."
prev_ni
Stored information about the state of the
dependency
the last time the
target
was built.
This can be consulted to match various
file characteristics
such as the timestamp,
size, or content signature.
The
function
should return a
True
(non-zero)
value if the
dependency
has "changed" since the last time
the
target
was built
(indicating that the target
should
be rebuilt),
and
False
(zero)
otherwise
(indicating that the target should
not
be rebuilt).
Note that the decision can be made
using whatever criteria are appopriate.
Ignoring some or all of the function arguments
is perfectly normal.
Example:
def my_decider(dependency, target, prev_ni): return not os.path.exists(str(target)) env.Decider(my_decider)
Default(targets)
,
env.Default(targets)
This specifies a list of default targets,
which will be built by
scons
if no explicit targets are given on the command line.
Multiple calls to
Default
are legal,
and add to the list of default targets.
Multiple targets should be specified as
separate arguments to the
Default
method, or as a list.
Default
will also accept the Node returned by any
of a construction environment's
builder methods.
Examples:
Default('foo', 'bar', 'baz') env.Default(['a', 'b', 'c']) hello = env.Program('hello', 'hello.c') env.Default(hello)
An argument to
Default
of
None
will clear all default targets.
Later calls to
Default
will add to the (now empty) default-target list
like normal.
The current list of targets added using the
Default
function or method is available in the
DEFAULT_TARGETS
list;
see below.
DefaultEnvironment([args])
Creates and returns a default construction environment object. This construction environment is used internally by SCons in order to execute many of the global functions in this list, and to fetch source files transparently from source code management systems.
Depends(target, dependency)
,
env.Depends(target, dependency)
Specifies an explicit dependency;
the
target
will be rebuilt
whenever the
dependency
has changed.
Both the specified
target
and
dependency
can be a string
(usually the path name of a file or directory)
or Node objects,
or a list of strings or Node objects
(such as returned by a Builder call).
This should only be necessary
for cases where the dependency
is not caught by a Scanner
for the file.
Example:
env.Depends('foo', 'other-input-file-for-foo') mylib = env.Library('mylib.c') installed_lib = env.Install('lib', mylib) bar = env.Program('bar.c') # Arrange for the library to be copied into the installation # directory before trying to build the "bar" program. # (Note that this is for example only. A "real" library # dependency would normally be configured through the $LIBS # and $LIBPATH variables, not using an env.Depends() call.) env.Depends(bar, installed_lib)
env.Dictionary([vars])
Returns a dictionary object containing copies of all of the construction variables in the environment. If there are any variable names specified, only the specified construction variables are returned in the dictionary.
Example:
dict = env.Dictionary() cc_dict = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')
Dir(name, [directory])
,
env.Dir(name, [directory])
This returns a Directory Node,
an object that represents the specified directory
name
.
name
can be a relative or absolute path.
directory
is an optional directory that will be used as the parent directory.
If no
directory
is specified, the current script's directory is used as the parent.
If
name
is a list, SCons returns a list of Dir nodes.
Construction variables are expanded in
name
.
Directory Nodes can be used anywhere you would supply a string as a directory name to a Builder method or function. Directory Nodes have attributes and methods that are useful in many situations; see "File and Directory Nodes," below.
env.Dump([key])
Returns a pretty printable representation of the environment.
key
,
if not
None
,
should be a string containing the name of the variable of interest.
This SConstruct:
env=Environment() print env.Dump('CCCOM')
will print:
'$CC -c -o $TARGET $CCFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS $SOURCES'
While this SConstruct:
env=Environment() print env.Dump()
will print:
{ 'AR': 'ar', 'ARCOM': '$AR $ARFLAGS $TARGET $SOURCES\n$RANLIB $RANLIBFLAGS $TARGET', 'ARFLAGS': ['r'], 'AS': 'as', 'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES', 'ASFLAGS': [], ...
EnsurePythonVersion(major, minor)
,
env.EnsurePythonVersion(major, minor)
Ensure that the Python version is at least
major
.minor
.
This function will
print out an error message and exit SCons with a non-zero exit code if the
actual Python version is not late enough.
Example:
EnsurePythonVersion(2,2)
EnsureSConsVersion(major, minor, [revision])
,
env.EnsureSConsVersion(major, minor, [revision])
Ensure that the SCons version is at least
major.minor
,
or
major.minor.revision
.
if
revision
is specified.
This function will
print out an error message and exit SCons with a non-zero exit code if the
actual SCons version is not late enough.
Examples:
EnsureSConsVersion(0,14) EnsureSConsVersion(0,96,90)
Environment([key=value, ...])
,
env.Environment([key=value, ...])
Return a new construction environment
initialized with the specified
key
=
value
pairs.
Execute(action, [strfunction, varlist])
,
env.Execute(action, [strfunction, varlist])
Executes an Action object.
The specified
action
may be an Action object
(see the section "Action Objects,"
below, for a complete explanation of the arguments and behavior),
or it may be a command-line string,
list of commands,
or executable Python function,
each of which will be converted
into an Action object
and then executed.
The exit value of the command
or return value of the Python function
will be returned.
Note that
scons
will print an error message if the executed
action
fails--that is,
exits with or returns a non-zero value.
scons
will
not,
however,
automatically terminate the build
if the specified
action
fails.
If you want the build to stop in response to a failed
Execute
call,
you must explicitly check for a non-zero return value:
Execute(Copy('file.out', 'file.in')) if Execute("mkdir sub/dir/ectory"): # The mkdir failed, don't try to build. Exit(1)
Exit([value])
,
env.Exit([value])
This tells
scons
to exit immediately
with the specified
value
.
A default exit value of
0
(zero)
is used if no value is specified.
Export(vars)
,
env.Export(vars)
This tells
scons
to export a list of variables from the current
SConscript file to all other SConscript files.
The exported variables are kept in a global collection,
so subsequent calls to
Export
will over-write previous exports that have the same name.
Multiple variable names can be passed to
Export
as separate arguments or as a list.
Keyword arguments can be used to provide names and their values.
A dictionary can be used to map variables to a different name when exported.
Both local variables and global variables can be exported.
Examples:
env = Environment() # Make env available for all SConscript files to Import(). Export("env") package = 'my_name' # Make env and package available for all SConscript files:. Export("env", "package") # Make env and package available for all SConscript files: Export(["env", "package"]) # Make env available using the name debug: Export(debug = env) # Make env available using the name debug: Export({"debug":env})
Note that the
SConscript
function supports an
exports
argument that makes it easier to to export a variable or
set of variables to a single SConscript file.
See the description of the
SConscript
function, below.
File(name, [directory])
,
env.File(name, [directory])
This returns a
File Node,
an object that represents the specified file
name
.
name
can be a relative or absolute path.
directory
is an optional directory that will be used as the parent directory.
If
name
is a list, SCons returns a list of File nodes.
Construction variables are expanded in
name
.
File Nodes can be used anywhere you would supply a string as a file name to a Builder method or function. File Nodes have attributes and methods that are useful in many situations; see "File and Directory Nodes," below.
FindFile(file, dirs)
,
env.FindFile(file, dirs)
Search for
file
in the path specified by
dirs
.
dirs
may be a list of directory names or a single directory name.
In addition to searching for files that exist in the filesystem,
this function also searches for derived files
that have not yet been built.
Example:
foo = env.FindFile('foo', ['dir1', 'dir2'])
FindInstalledFiles()
,
env.FindInstalledFiles()
Returns the list of targets set up by the
Install
or
InstallAs
builders.
This function serves as a convenient method to select the contents of a binary package.
Example:
Install( '/bin', [ 'executable_a', 'executable_b' ] ) # will return the file node list # [ '/bin/executable_a', '/bin/executable_b' ] FindInstalledFiles() Install( '/lib', [ 'some_library' ] ) # will return the file node list # [ '/bin/executable_a', '/bin/executable_b', '/lib/some_library' ] FindInstalledFiles()
FindPathDirs(variable)
Returns a function
(actually a callable Python object)
intended to be used as the
path_function
of a Scanner object.
The returned object will look up the specified
variable
in a construction environment
and treat the construction variable's value as a list of
directory paths that should be searched
(like
$CPPPATH
,
$LIBPATH
,
etc.).
Note that use of
FindPathDirs
is generally preferable to
writing your own
path_function
for the following reasons:
1) The returned list will contain all appropriate directories
found in source trees
(when
VariantDir
is used)
or in code repositories
(when
Repository
or the
-Y
option are used).
2) scons will identify expansions of
variable
that evaluate to the same list of directories as,
in fact, the same list,
and avoid re-scanning the directories for files,
when possible.
Example:
def my_scan(node, env, path, arg): # Code to scan file contents goes here... return include_files scanner = Scanner(name = 'myscanner', function = my_scan, path_function = FindPathDirs('MYPATH'))
FindSourceFiles(node='"."')
,
env.FindSourceFiles(node='"."')
Returns the list of nodes which serve as the source of the built files.
It does so by inspecting the dependency tree starting at the optional
argument
node
which defaults to the '"."'-node. It will then return all leaves of
node
.
These are all children which have no further children.
This function is a convenient method to select the contents of a Source Package.
Example:
Program( 'src/main_a.c' ) Program( 'src/main_b.c' ) Program( 'main_c.c' ) # returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c'] FindSourceFiles() # returns ['src/main_b.c', 'src/main_a.c' ] FindSourceFiles( 'src' )
As you can see build support files (SConstruct in the above example) will also be returned by this function.
Flatten(sequence)
,
env.Flatten(sequence)
Takes a sequence (that is, a Python list or tuple) that may contain nested sequences and returns a flattened list containing all of the individual elements in any sequence. This can be helpful for collecting the lists returned by calls to Builders; other Builders will automatically flatten lists specified as input, but direct Python manipulation of these lists does not.
Examples:
foo = Object('foo.c') bar = Object('bar.c') # Because `foo' and `bar' are lists returned by the Object() Builder, # `objects' will be a list containing nested lists: objects = ['f1.o', foo, 'f2.o', bar, 'f3.o'] # Passing such a list to another Builder is all right because # the Builder will flatten the list automatically: Program(source = objects) # If you need to manipulate the list directly using Python, you need to # call Flatten() yourself, or otherwise handle nested lists: for object in Flatten(objects): print str(object)
GetBuildFailures()
Returns a list of exceptions for the
actions that failed while
attempting to build targets.
Each element in the returned list is a
BuildError
object
with the following attributes
that record various aspects
of the build failure:
.node
The node that was being built
when the build failure occurred.
.status
The numeric exit status
returned by the command or Python function
that failed when trying to build the
specified Node.
.errstr
The SCons error string
describing the build failure.
(This is often a generic
message like "Error 2"
to indicate that an executed
command exited with a status of 2.)
.filename
The name of the file or
directory that actually caused the failure.
This may be different from the
.node
attribute.
For example,
if an attempt to build a target named
sub/dir/target
fails because the
sub/dir
directory could not be created,
then the
.node
attribute will be
sub/dir/target
but the
.filename
attribute will be
sub/dir
.
.executor
The SCons Executor object
for the target Node
being built.
This can be used to retrieve
the construction environment used
for the failed action.
.action
The actual SCons Action object that failed.
This will be one specific action
out of the possible list of
actions that would have been
executed to build the target.
.command
The actual expanded command that was executed and failed,
after expansion of
$TARGET
,
$SOURCE
,
and other construction variables.
Note that the
GetBuildFailures
function
will always return an empty list
until any build failure has occurred,
which means that
GetBuildFailures
will always return an empty list
while the
SConscript
files are being read.
Its primary intended use is
for functions that will be
executed before SCons exits
by passing them to the
standard Python
atexit.register
()
function.
Example:
import atexit def print_build_failures(): from SCons.Script import GetBuildFailures for bf in GetBuildFailures(): print("%s failed: %s" % (bf.node, bf.errstr)) atexit.register(print_build_failures)
GetBuildPath(file, [...])
,
env.GetBuildPath(file, [...])
Returns the
scons
path name (or names) for the specified
file
(or files).
The specified
file
or files
may be
scons
Nodes or strings representing path names.
GetLaunchDir()
,
env.GetLaunchDir()
Returns the absolute path name of the directory from which
scons
was initially invoked.
This can be useful when using the
-u
,
-U
or
-D
options, which internally
change to the directory in which the
SConstruct
file is found.
GetOption(name)
,
env.GetOption(name)
This function provides a way to query the value of
SCons options set on scons command line
(or set using the
SetOption
function).
The options supported are:
cache_debug
which corresponds to --cache-debug;
cache_disable
which corresponds to --cache-disable;
cache_force
which corresponds to --cache-force;
cache_show
which corresponds to --cache-show;
clean
which corresponds to -c, --clean and --remove;
config
which corresponds to --config;
directory
which cor