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 corresponds to -C and --directory;
diskcheck
which corresponds to --diskcheck
duplicate
which corresponds to --duplicate;
file
which corresponds to -f, --file, --makefile and --sconstruct;
help
which corresponds to -h and --help;
ignore_errors
which corresponds to --ignore-errors;
implicit_cache
which corresponds to --implicit-cache;
implicit_deps_changed
which corresponds to --implicit-deps-changed;
implicit_deps_unchanged
which corresponds to --implicit-deps-unchanged;
interactive
which corresponds to --interact and --interactive;
keep_going
which corresponds to -k and --keep-going;
max_drift
which corresponds to --max-drift;
no_exec
which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;
no_site_dir
which corresponds to --no-site-dir;
num_jobs
which corresponds to -j and --jobs;
profile_file
which corresponds to --profile;
question
which corresponds to -q and --question;
random
which corresponds to --random;
repository
which corresponds to -Y, --repository and --srcdir;
silent
which corresponds to -s, --silent and --quiet;
site_dir
which corresponds to --site-dir;
stack_size
which corresponds to --stack-size;
taskmastertrace_file
which corresponds to --taskmastertrace; and
warn
which corresponds to --warn and --warning.
See the documentation for the corresponding command line object for information about each specific option.
Glob(pattern, [ondisk, source, strings, exclude])
,
env.Glob(pattern, [ondisk, source, strings, exclude])
Returns Nodes (or strings) that match the specified
pattern
,
relative to the directory of the current
SConscript
file.
The
env.Glob
()
form performs string substition on
pattern
and returns whatever matches
the resulting expanded pattern.
The specified
pattern
uses Unix shell style metacharacters for matching:
* matches everything ? matches any single character [seq] matches any character in seq [!seq] matches any char not in seq
If the first character of a filename is a dot, it must be matched explicitly. Character matches do not span directory separators.
The
Glob
knows about
repositories
(see the
Repository
function)
and source directories
(see the
VariantDir
function)
and
returns a Node (or string, if so configured)
in the local (SConscript) directory
if matching Node is found
anywhere in a corresponding
repository or source directory.
The
ondisk
argument may be set to
False
(or any other non-true value)
to disable the search for matches on disk,
thereby only returning matches among
already-configured File or Dir Nodes.
The default behavior is to
return corresponding Nodes
for any on-disk matches found.
The
source
argument may be set to
True
(or any equivalent value)
to specify that,
when the local directory is a
VariantDir
,
the returned Nodes should be from the
corresponding source directory,
not the local directory.
The
strings
argument may be set to
True
(or any equivalent value)
to have the
Glob
function return strings, not Nodes,
that represent the matched files or directories.
The returned strings will be relative to
the local (SConscript) directory.
(Note that This may make it easier to perform
arbitrary manipulation of file names,
but if the returned strings are
passed to a different
SConscript
file,
any Node translation will be relative
to the other
SConscript
directory,
not the original
SConscript
directory.)
The
exclude
argument may be set to a pattern or a list of patterns
(following the same Unix shell semantics)
which must be filtered out of returned elements.
Elements matching a least one pattern of
this list will be excluded.
Examples:
Program('foo', Glob('*.c')) Zip('/tmp/everything', Glob('.??*') + Glob('*')) sources = Glob('*.cpp', exclude=['os_*_specific_*.cpp']) + Glob('os_%s_specific_*.cpp'%currentOS)
Help(text, append=False)
,
env.Help(text, append=False)
This specifies help text to be printed if the
-h
argument is given to
scons
.
If
Help
is called multiple times, the text is appended together in the order that
Help
is called. With append set to False, any
Help
text generated with
AddOption
is clobbered. If append is True, the AddOption help is prepended to the help
string, thus preserving the
-h
message.
Ignore(target, dependency)
,
env.Ignore(target, dependency)
The specified dependency file(s) will be ignored when deciding if the target file(s) need to be rebuilt.
You can also use
Ignore
to remove a target from the default build.
In order to do this you must specify the directory the target will
be built in as the target, and the file you want to skip building
as the dependency.
Note that this will only remove the dependencies listed from the files built by default. It will still be built if that dependency is needed by another object being built. See the third and forth examples below.
Examples:
env.Ignore('foo', 'foo.c') env.Ignore('bar', ['bar1.h', 'bar2.h']) env.Ignore('.','foobar.obj') env.Ignore('bar','bar/foobar.obj')
Import(vars)
,
env.Import(vars)
This tells
scons
to import a list of variables into the current SConscript file. This
will import variables that were exported with
Export
or in the
exports
argument to
SConscript
.
Variables exported by
SConscript
have precedence.
Multiple variable names can be passed to
Import
as separate arguments or as a list. The variable "*" can be used
to import all variables.
Examples:
Import("env") Import("env", "variable") Import(["env", "variable"]) Import("*")
Literal(string)
,
env.Literal(string)
The specified
string
will be preserved as-is
and not have construction variables expanded.
Local(targets)
,
env.Local(targets)
The specified
targets
will have copies made in the local tree,
even if an already up-to-date copy
exists in a repository.
Returns a list of the target Node or Nodes.
env.MergeFlags(arg, [unique])
Merges the specified
arg
values to the construction environment's construction variables.
If the
arg
argument is not a dictionary,
it is converted to one by calling
env.ParseFlags
on the argument
before the values are merged.
Note that
arg
must be a single value,
so multiple strings must
be passed in as a list,
not as separate arguments to
env.MergeFlags
.
By default,
duplicate values are eliminated;
you can, however, specify
unique=0
to allow duplicate
values to be added.
When eliminating duplicate values,
any construction variables that end with
the string
PATH
keep the left-most unique value.
All other construction variables keep
the right-most unique value.
Examples:
# Add an optimization flag to $CCFLAGS. env.MergeFlags('-O3') # Combine the flags returned from running pkg-config with an optimization # flag and merge the result into the construction variables. env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3']) # Combine an optimization flag with the flags returned from running pkg-config # twice and merge the result into the construction variables. env.MergeFlags(['-O3', '!pkg-config gtk+-2.0 --cflags --libs', '!pkg-config libpng12 --cflags --libs'])
NoCache(target, ...)
,
env.NoCache(target, ...)
Specifies a list of files which should
not
be cached whenever the
CacheDir
method has been activated.
The specified targets may be a list
or an individual target.
Multiple files should be specified
either as separate arguments to the
NoCache
method, or as a list.
NoCache
will also accept the return value of any of the construction environment
Builder methods.
Calling
NoCache
on directories and other non-File Node types has no effect because
only File Nodes are cached.
Examples:
NoCache('foo.elf') NoCache(env.Program('hello', 'hello.c'))
NoClean(target, ...)
,
env.NoClean(target, ...)
Specifies a list of files or directories which should
not
be removed whenever the targets (or their dependencies)
are specified with the
-c
command line option.
The specified targets may be a list
or an individual target.
Multiple calls to
NoClean
are legal,
and prevent each specified target
from being removed by calls to the
-c
option.
Multiple files or directories should be specified
either as separate arguments to the
NoClean
method, or as a list.
NoClean
will also accept the return value of any of the construction environment
Builder methods.
Calling
NoClean
for a target overrides calling
Clean
for the same target,
and any targets passed to both functions will
not
be removed by the
-c
option.
Examples:
NoClean('foo.elf') NoClean(env.Program('hello', 'hello.c'))
env.ParseConfig(command, [function, unique])
Calls the specified
function
to modify the environment as specified by the output of
command
.
The default
function
is
env.MergeFlags
,
which expects the output of a typical
*-config
command
(for example,
gtk-config)
and adds the options
to the appropriate construction variables.
By default,
duplicate values are not
added to any construction variables;
you can specify
unique=0
to allow duplicate
values to be added.
Interpreted options
and the construction variables they affect
are as specified for the
env.ParseFlags
method (which this method calls).
See that method's description, below,
for a table of options and construction variables.
ParseDepends(filename, [must_exist, only_one])
,
env.ParseDepends(filename, [must_exist, only_one])
Parses the contents of the specified
filename
as a list of dependencies in the style of
Make
or
mkdep,
and explicitly establishes all of the listed dependencies.
By default,
it is not an error
if the specified
filename
does not exist.
The optional
must_exist
argument may be set to a non-zero
value to have
scons
throw an exception and
generate an error if the file does not exist,
or is otherwise inaccessible.
The optional
only_one
argument may be set to a non-zero
value to have
scons
thrown an exception and
generate an error
if the file contains dependency
information for more than one target.
This can provide a small sanity check
for files intended to be generated
by, for example, the
gcc -M
flag,
which should typically only
write dependency information for
one output file into a corresponding
.d
file.
The
filename
and all of the files listed therein
will be interpreted relative to
the directory of the
SConscript
file which calls the
ParseDepends
function.
env.ParseFlags(flags, ...)
Parses one or more strings containing
typical command-line flags for GCC tool chains
and returns a dictionary with the flag values
separated into the appropriate SCons construction variables.
This is intended as a companion to the
env.MergeFlags
method, but allows for the values in the returned dictionary
to be modified, if necessary,
before merging them into the construction environment.
(Note that
env.MergeFlags
will call this method if its argument is not a dictionary,
so it is usually not necessary to call
env.ParseFlags
directly unless you want to manipulate the values.)
If the first character in any string is an exclamation mark (!), the rest of the string is executed as a command, and the output from the command is parsed as GCC tool chain command-line flags and added to the resulting dictionary.
Flag values are translated accordig to the prefix found, and added to the following construction variables:
-arch CCFLAGS, LINKFLAGS -D CPPDEFINES -framework FRAMEWORKS -frameworkdir= FRAMEWORKPATH -include CCFLAGS -isysroot CCFLAGS, LINKFLAGS -I CPPPATH -l LIBS -L LIBPATH -mno-cygwin CCFLAGS, LINKFLAGS -mwindows LINKFLAGS -pthread CCFLAGS, LINKFLAGS -std= CFLAGS -Wa, ASFLAGS, CCFLAGS -Wl,-rpath= RPATH -Wl,-R, RPATH -Wl,-R RPATH -Wl, LINKFLAGS -Wp, CPPFLAGS - CCFLAGS + CCFLAGS, LINKFLAGS
Any other strings not associated with options
are assumed to be the names of libraries
and added to the
$LIBS
construction variable.
Examples (all of which produce the same result):
dict = env.ParseFlags('-O2 -Dfoo -Dbar=1') dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1') dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1']) dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')
Platform(string)
The
Platform
form returns a callable object
that can be used to initialize
a construction environment using the
platform keyword of the
Environment
function.
Example:
env = Environment(platform = Platform('win32'))
The
env.Platform
form applies the callable object for the specified platform
string
to the environment through which the method was called.
env.Platform('posix')
Note that the
win32
platform adds the
SystemDrive
and
SystemRoot
variables from the user's external environment
to the construction environment's
$ENV
dictionary.
This is so that any executed commands
that use sockets to connect with other systems
(such as fetching source files from
external CVS repository specifications like
:pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons
)
will work on Windows systems.
Precious(target, ...)
,
env.Precious(target, ...)
Marks each given
target
as precious so it is not deleted before it is rebuilt. Normally
scons
deletes a target before building it.
Multiple targets can be passed in to a single call to
Precious
.
env.Prepend(key=val, [...])
Appends the specified keyword arguments to the beginning of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the values of the construction variable and the keyword argument are the same type, then the two values will be simply added together. Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. (See also the Append method, above.)
Example:
env.Prepend(CCFLAGS = '-g ', FOO = ['foo.yyy'])
env.PrependENVPath(name, newpath, [envname, sep, delete_existing])
This appends new path elements to the given path in the
specified external environment
($ENV
by default).
This will only add
any particular path once (leaving the first 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 beginning;
it will stay where it is in the list.
Example:
print 'before:',env['ENV']['INCLUDE'] include_path = '/foo/bar:/foo' env.PrependENVPath('INCLUDE', include_path) print 'after:',env['ENV']['INCLUDE']
The above example will print:
before: /biz:/foo after: /foo/bar:/foo:/biz
env.PrependUnique(key=val, delete_existing=0, [...])
Appends the specified keyword arguments to the beginning 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 front of the list.
Example:
env.PrependUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])
Progress(callable, [interval])
,
Progress(string, [interval, file, overwrite])
,
Progress(list_of_strings, [interval, file, overwrite])
Allows SCons to show progress made during the build by displaying a string or calling a function while evaluating Nodes (e.g. files).
If the first specified argument is a Python callable
(a function or an object that has a
__call__
()
method),
the function will be called
once every
interval
times a Node is evaluated.
The callable will be passed the evaluated Node
as its only argument.
(For future compatibility,
it's a good idea to also add
*args
and
**kw
as arguments to your function or method.
This will prevent the code from breaking
if SCons ever changes the interface
to call the function with additional arguments in the future.)
An example of a simple custom progress function that prints a string containing the Node name every 10 Nodes:
def my_progress_function(node, *args, **kw): print('Evaluating node %s!' % node) Progress(my_progress_function, interval=10)
A more complicated example of a custom progress display object
that prints a string containing a count
every 100 evaluated Nodes.
Note the use of
\r
(a carriage return)
at the end so that the string
will overwrite itself on a display:
import sys class ProgressCounter(object): count = 0 def __call__(self, node, *args, **kw): self.count += 100 sys.stderr.write('Evaluated %s nodes\r' % self.count) Progress(ProgressCounter(), interval=100)
If the first argument
Progress
is a string,
the string will be displayed
every
interval
evaluated Nodes.
The default is to print the string on standard output;
an alternate output stream
may be specified with the
file=
argument.
The following will print a series of dots
on the error output,
one dot for every 100 evaluated Nodes:
import sys Progress('.', interval=100, file=sys.stderr)
If the string contains the verbatim substring
$TARGET
,
it will be replaced with the Node.
Note that, for performance reasons, this is
not
a regular SCons variable substition,
so you can not use other variables
or use curly braces.
The following example will print the name of
every evaluated Node,
using a
\r
(carriage return) to cause each line to overwritten by the next line,
and the
overwrite=
keyword argument to make sure the previously-printed
file name is overwritten with blank spaces:
import sys Progress('$TARGET\r', overwrite=True)
If the first argument to
Progress
is a list of strings,
then each string in the list will be displayed
in rotating fashion every
interval
evaluated Nodes.
This can be used to implement a "spinner"
on the user's screen as follows:
Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)
Pseudo(target, ...)
,
env.Pseudo(target, ...)
This indicates that each given
target
should not be created by the build rule, and if the target is created,
an error will be generated. This is similar to the gnu make .PHONY
target. However, in the vast majority of cases, an
Alias
is more appropriate.
Multiple targets can be passed in to a single call to
Pseudo
.
PyPackageDir(modulename)
,
env.PyPackageDir(modulename)
This returns a Directory Node similar to Dir.
The python module / package is looked up and if located
the directory is returned for the location.
modulename
Is a named python package / module to
lookup the directory for it's location.
If
modulename
is a list, SCons returns a list of Dir nodes.
Construction variables are expanded in
modulename
.
env.Replace(key=val, [...])
Replaces construction variables in the Environment with the specified keyword arguments.
Example:
env.Replace(CCFLAGS = '-g', FOO = 'foo.xxx')
Repository(directory)
,
env.Repository(directory)
Specifies that
directory
is a repository to be searched for files.
Multiple calls to
Repository
are legal,
and each one adds to the list of
repositories that will be searched.
To
scons
,
a repository is a copy of the source tree,
from the top-level directory on down,
which may contain
both source files and derived files
that can be used to build targets in
the local source tree.
The canonical example would be an
official source tree maintained by an integrator.
If the repository contains derived files,
then the derived files should have been built using
scons
,
so that the repository contains the necessary
signature information to allow
scons
to figure out when it is appropriate to
use the repository copy of a derived file,
instead of building one locally.
Note that if an up-to-date derived file
already exists in a repository,
scons
will
not
make a copy in the local directory tree.
In order to guarantee that a local copy
will be made,
use the
Local
method.
Requires(target, prerequisite)
,
env.Requires(target, prerequisite)
Specifies an order-only relationship between the specified target file(s) and the specified prerequisite file(s). The prerequisite file(s) will be (re)built, if necessary, before the target file(s), but the target file(s) do not actually depend on the prerequisites and will not be rebuilt simply because the prerequisite file(s) change.
Example:
env.Requires('foo', 'file-that-must-be-built-before-foo')
Return([vars..., stop=])
By default,
this stops processing the current SConscript
file and returns to the calling SConscript file
the values of the variables named in the
vars
string arguments.
Multiple strings contaning variable names may be passed to
Return
.
Any strings that contain white space
The optional
stop=
keyword argument may be set to a false value
to continue processing the rest of the SConscript
file after the
Return
call.
This was the default behavior prior to SCons 0.98.
However, the values returned
are still the values of the variables in the named
vars
at the point
Return
is called.
Examples:
# Returns without returning a value. Return() # Returns the value of the 'foo' Python variable. Return("foo") # Returns the values of the Python variables 'foo' and 'bar'. Return("foo", "bar") # Returns the values of Python variables 'val1' and 'val2'. Return('val1 val2')
Scanner(function, [argument, keys, path_function, node_class, node_factory, scan_check, recursive])
,
env.Scanner(function, [argument, keys, path_function, node_class, node_factory, scan_check, recursive])
Creates a Scanner object for
the specified
function
.
See the section "Scanner Objects,"
below, for a complete explanation of the arguments and behavior.
SConscript(scripts, [exports, variant_dir, duplicate])
,
env.SConscript(scripts, [exports, variant_dir, duplicate])
,
SConscript(dirs=subdirs, [name=script, exports, variant_dir, duplicate])
,
env.SConscript(dirs=subdirs, [name=script, exports, variant_dir, duplicate])
This tells
scons
to execute
one or more subsidiary SConscript (configuration) files.
Any variables returned by a called script using
Return
will be returned by the call to
SConscript
.
There are two ways to call the
SConscript
function.
The first way you can call
SConscript
is to explicitly specify one or more
scripts
as the first argument.
A single script may be specified as a string;
multiple scripts must be specified as a list
(either explicitly or as created by
a function like
Split
).
Examples:
SConscript('SConscript') # run SConscript in the current directory SConscript('src/SConscript') # run SConscript in the src directory SConscript(['src/SConscript', 'doc/SConscript']) config = SConscript('MyConfig.py')
The second way you can call
SConscript
is to specify a list of (sub)directory names
as a
dirs=
subdirs
keyword argument.
In this case,
scons
will, by default,
execute a subsidiary configuration file named
SConscript
in each of the specified directories.
You may specify a name other than
SConscript
by supplying an optional
name=
script
keyword argument.
The first three examples below have the same effect
as the first three examples above:
SConscript(dirs='.') # run SConscript in the current directory SConscript(dirs='src') # run SConscript in the src directory SConscript(dirs=['src', 'doc']) SConscript(dirs=['sub1', 'sub2'], name='MySConscript')
The optional
exports
argument provides a list of variable names or a dictionary of
named values to export to the
script(s)
.
These variables are locally exported only to the specified
script(s)
,
and do not affect the global pool of variables used by the
Export
function.
The subsidiary
script(s)
must use the
Import
function to import the variables.
Examples:
foo = SConscript('sub/SConscript', exports='env') SConscript('dir/SConscript', exports=['env', 'variable']) SConscript(dirs='subdir', exports='env variable') SConscript(dirs=['one', 'two', 'three'], exports='shared_info')
If the optional
variant_dir
argument is present, it causes an effect equivalent to the
VariantDir
method described below.
(If
variant_dir
is not present, the
duplicate
argument is ignored.)
The
variant_dir
argument is interpreted relative to the directory of the calling
SConscript
file.
See the description of the
VariantDir
function below for additional details and restrictions.
If
variant_dir
is present,
the source directory is the directory in which the
SConscript
file resides and the
SConscript
file is evaluated as if it were in the
variant_dir
directory:
SConscript('src/SConscript', variant_dir = 'build')
is equivalent to
VariantDir('build', 'src') SConscript('build/SConscript')
This later paradigm is often used when the sources are
in the same directory as the
SConstruct
:
SConscript('SConscript', variant_dir = 'build')
is equivalent to
VariantDir('build', '.') SConscript('build/SConscript')
Here are some composite examples:
# collect the configuration information and use it to build src and doc shared_info = SConscript('MyConfig.py') SConscript('src/SConscript', exports='shared_info') SConscript('doc/SConscript', exports='shared_info')
# build debugging and production versions. SConscript # can use Dir('.').path to determine variant. SConscript('SConscript', variant_dir='debug', duplicate=0) SConscript('SConscript', variant_dir='prod', duplicate=0)
# build debugging and production versions. SConscript # is passed flags to use. opts = { 'CPPDEFINES' : ['DEBUG'], 'CCFLAGS' : '-pgdb' } SConscript('SConscript', variant_dir='debug', duplicate=0, exports=opts) opts = { 'CPPDEFINES' : ['NODEBUG'], 'CCFLAGS' : '-O' } SConscript('SConscript', variant_dir='prod', duplicate=0, exports=opts)
# build common documentation and compile for different architectures SConscript('doc/SConscript', variant_dir='build/doc', duplicate=0) SConscript('src/SConscript', variant_dir='build/x86', duplicate=0) SConscript('src/SConscript', variant_dir='build/ppc', duplicate=0)
SConscriptChdir(value)
,
env.SConscriptChdir(value)
By default,
scons
changes its working directory
to the directory in which each
subsidiary SConscript file lives.
This behavior may be disabled
by specifying either:
SConscriptChdir(0) env.SConscriptChdir(0)
in which case
scons
will stay in the top-level directory
while reading all SConscript files.
(This may be necessary when building from repositories,
when all the directories in which SConscript files may be found
don't necessarily exist locally.)
You may enable and disable
this ability by calling
SConscriptChdir()
multiple times.
Example:
env = Environment() SConscriptChdir(0) SConscript('foo/SConscript') # will not chdir to foo env.SConscriptChdir(1) SConscript('bar/SConscript') # will chdir to bar
SConsignFile([file, dbm_module])
,
env.SConsignFile([file, dbm_module])
This tells
scons
to store all file signatures
in the specified database
file
.
If the
file
name is omitted,
.sconsign
is used by default.
(The actual file name(s) stored on disk
may have an appropriated suffix appended
by the
dbm_module
.)
If
file
is not an absolute path name,
the file is placed in the same directory as the top-level
SConstruct
file.
If
file
is
None
,
then
scons
will store file signatures
in a separate
.sconsign
file in each directory,
not in one global database file.
(This was the default behavior
prior to SCons 0.96.91 and 0.97.)
The optional
dbm_module
argument can be used to specify
which Python database module
The default is to use a custom
SCons.dblite
module that uses pickled
Python data structures,
and which works on all Python versions.
Examples:
# Explicitly stores signatures in ".sconsign.dblite" # in the top-level SConstruct directory (the # default behavior). SConsignFile() # Stores signatures in the file "etc/scons-signatures" # relative to the top-level SConstruct directory. SConsignFile("etc/scons-signatures") # Stores signatures in the specified absolute file name. SConsignFile("/home/me/SCons/signatures") # Stores signatures in a separate .sconsign file # in each directory. SConsignFile(None)
env.SetDefault(key=val, [...])
Sets construction variables to default values specified with the keyword arguments if (and only if) the variables are not already set. The following statements are equivalent:
env.SetDefault(FOO = 'foo') if 'FOO' not in env: env['FOO'] = 'foo'
SetOption(name, value)
,
env.SetOption(name, value)
This function provides a way to set a select subset of the scons command line options from a SConscript file. The options supported are:
clean
which corresponds to -c, --clean and --remove;
duplicate
which corresponds to --duplicate;
help
which corresponds to -h and --help;
implicit_cache
which corresponds to --implicit-cache;
max_drift
which corresponds to --max-drift;
no_exec
which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;
num_jobs
which corresponds to -j and --jobs;
random
which corresponds to --random; and
silent
which corresponds to --silent.
stack_size
which corresponds to --stack-size.
See the documentation for the corresponding command line object for information about each specific option.
Example:
SetOption('max_drift', 1)
SideEffect(side_effect, target)
,
env.SideEffect(side_effect, target)
Declares
side_effect
as a side effect of building
target
.
Both
side_effect
and
target
can be a list, a file name, or a node.
A side effect is a target file that is created or updated
as a side effect of building other targets.
For example, a Windows PDB
file is created as a side effect of building the .obj
files for a static library,
and various log files are created updated
as side effects of various TeX commands.
If a target is a side effect of multiple build commands,
scons
will ensure that only one set of commands
is executed at a time.
Consequently, you only need to use this method
for side-effect targets that are built as a result of
multiple build commands.
Because multiple build commands may update
the same side effect file,
by default the
side_effect
target is
not
automatically removed
when the
target
is removed by the
-c
option.
(Note, however, that the
side_effect
might be removed as part of
cleaning the directory in which it lives.)
If you want to make sure the
side_effect
is cleaned whenever a specific
target
is cleaned,
you must specify this explicitly
with the
Clean
or
env.Clean
function.
SourceCode(entries, builder)
,
env.SourceCode(entries, builder)
This function and its associate factory functions are deprecated. There is no replacement. The intended use was to keep a local tree in sync with an archive, but in actuality the function only causes the archive to be fetched on the first run. Synchronizing with the archive is best done external to SCons.
Arrange for non-existent source files to
be fetched from a source code management system
using the specified
builder
.
The specified
entries
may be a Node, string or list of both,
and may represent either individual
source files or directories in which
source files can be found.
For any non-existent source files,
scons
will search up the directory tree
and use the first
SourceCode
builder it finds.
The specified
builder
may be
None
,
in which case
scons
will not use a builder to fetch
source files for the specified
entries
,
even if a
SourceCode
builder has been specified
for a directory higher up the tree.
scons
will, by default,
fetch files from SCCS or RCS subdirectories
without explicit configuration.
This takes some extra processing time
to search for the necessary
source code management files on disk.
You can avoid these extra searches
and speed up your build a little
by disabling these searches as follows:
env.SourceCode('.', None)
Note that if the specified
builder
is one you create by hand,
it must have an associated
construction environment to use
when fetching a source file.
scons
provides a set of canned factory
functions that return appropriate
Builders for various popular
source code management systems.
Canonical examples of invocation include:
env.SourceCode('.', env.BitKeeper('/usr/local/BKsources')) env.SourceCode('src', env.CVS('/usr/local/CVSROOT')) env.SourceCode('/', env.RCS()) env.SourceCode(['f1.c', 'f2.c'], env.SCCS()) env.SourceCode('no_source.c', None)
SourceSignatures(type)
,
env.SourceSignatures(type)
Note: Although it is not yet officially deprecated,
use of this function is discouraged.
See the
Decider
function for a more flexible and straightforward way
to configure SCons' decision-making.
The
SourceSignatures
function tells
scons
how to decide if a source file
(a file that is not built from any other files)
has changed since the last time it
was used to build a particular target file.
Legal values are
MD5
or
timestamp
.
If the environment method is used, the specified type of source signature is only used when deciding whether targets built with that environment are up-to-date or must be rebuilt. If the global function is used, the specified type of source signature becomes the default used for all decisions about whether targets are up-to-date.
MD5
means
scons
decides that a source file has changed
if the MD5 checksum of its contents has changed since
the last time it was used to rebuild a particular target file.
timestamp
means
scons
decides that a source file has changed
if its timestamp (modification time) has changed since
the last time it was used to rebuild a particular target file.
(Note that although this is similar to the behavior of Make,
by default it will also rebuild if the dependency is
older
than the last time it was used to rebuild the target file.)
There is no different between the two behaviors
for Python
Value
node objects.
MD5
signatures take longer to compute,
but are more accurate than
timestamp
signatures.
The default value is
MD5
.
Note that the default
TargetSignatures
setting (see below)
is to use this
SourceSignatures
setting for any target files that are used
to build other target files.
Consequently, changing the value of
SourceSignatures
will, by default,
affect the up-to-date decision for all files in the build
(or all files built with a specific construction environment
when
env.SourceSignatures
is used).
Split(arg)
,
env.Split(arg)
Returns a list of file names or other objects. If arg is a string, it will be split on strings of white-space characters within the string, making it easier to write long lists of file names. If arg is already a list, the list will be returned untouched. If arg is any other type of object, it will be returned as a list containing just the object.
Example:
files = Split("f1.c f2.c f3.c") files = env.Split("f4.c f5.c f6.c") files = Split(""" f7.c f8.c f9.c """)
env.subst(input, [raw, target, source, conv])
Performs construction variable interpolation
on the specified string or sequence argument
input
.
By default,
leading or trailing white space will
be removed from the result.
and all sequences of white space
will be compressed to a single space character.
Additionally, any
$(
and
$)
character sequences will be stripped from the returned string,
The optional
raw
argument may be set to
1
if you want to preserve white space and
$(
-$)
sequences.
The
raw
argument may be set to
2
if you want to strip
all characters between
any
$(
and
$)
pairs
(as is done for signature calculation).
If the input is a sequence (list or tuple), the individual elements of the sequence will be expanded, and the results will be returned as a list.
The optional
target
and
source
keyword arguments
must be set to lists of
target and source nodes, respectively,
if you want the
$TARGET
,
$TARGETS
,
$SOURCE
and
$SOURCES
to be available for expansion.
This is usually necessary if you are
calling
env.subst
from within a Python function used
as an SCons action.
Returned string values or sequence elements
are converted to their string representation by default.
The optional
conv
argument
may specify a conversion function
that will be used in place of
the default.
For example, if you want Python objects
(including SCons Nodes)
to be returned as Python objects,
you can use the Python
Λ
idiom to pass in an unnamed function
that simply returns its unconverted argument.
Example:
print env.subst("The C compiler is: $CC") def compile(target, source, env): sourceDir = env.subst("${SOURCE.srcdir}", target=target, source=source) source_nodes = env.subst('$EXPAND_TO_NODELIST', conv=lambda x: x)
Tag(node, tags)
Annotates file or directory Nodes with
information about how the
Package
Builder should package those files or directories.
All tags are optional.
Examples:
# makes sure the built library will be installed with 0644 file # access mode Tag( Library( 'lib.c' ), UNIX_ATTR="0644" ) # marks file2.txt to be a documentation file Tag( 'file2.txt', DOC )
TargetSignatures(type)
,
env.TargetSignatures(type)
Note: Although it is not yet officially deprecated,
use of this function is discouraged.
See the
Decider
function for a more flexible and straightforward way
to configure SCons' decision-making.
The
TargetSignatures
function tells
scons
how to decide if a target file
(a file that
is
built from any other files)
has changed since the last time it
was used to build some other target file.
Legal values are
"build"
;
"content"
(or its synonym
"MD5"
);
"timestamp"
;
or
"source"
.
If the environment method is used, the specified type of target signature is only used for targets built with that environment. If the global function is used, the specified type of signature becomes the default used for all target files that don't have an explicit target signature type specified for their environments.
"content"
(or its synonym
"MD5"
)
means
scons
decides that a target file has changed
if the MD5 checksum of its contents has changed since
the last time it was used to rebuild some other target file.
This means
scons
will open up
MD5 sum the contents
of target files after they're built,
and may decide that it does not need to rebuild
"downstream" target files if a file was
rebuilt with exactly the same contents as the last time.
"timestamp"
means
scons
decides that a target file has changed
if its timestamp (modification time) has changed since
the last time it was used to rebuild some other target file.
(Note that although this is similar to the behavior of Make,
by default it will also rebuild if the dependency is
older
than the last time it was used to rebuild the target file.)
"source"
means
scons
decides that a target file has changed
as specified by the corresponding
SourceSignatures
setting
("MD5"
or
"timestamp"
).
This means that
scons
will treat all input files to a target the same way,
regardless of whether they are source files
or have been built from other files.
"build"
means
scons
decides that a target file has changed
if it has been rebuilt in this invocation
or if its content or timestamp have changed
as specified by the corresponding
SourceSignatures
setting.
This "propagates" the status of a rebuilt file
so that other "downstream" target files
will always be rebuilt,
even if the contents or the timestamp
have not changed.
"build"
signatures are fastest because
"content"
(or
"MD5"
)
signatures take longer to compute,
but are more accurate than
"timestamp"
signatures,
and can prevent unnecessary "downstream" rebuilds
when a target file is rebuilt to the exact same contents
as the previous build.
The
"source"
setting provides the most consistent behavior
when other target files may be rebuilt from
both source and target input files.
The default value is
"source"
.
Because the default setting is
"source"
,
using
SourceSignatures
is generally preferable to
TargetSignatures
,
so that the up-to-date decision
will be consistent for all files
(or all files built with a specific construction environment).
Use of
TargetSignatures
provides specific control for how built target files
affect their "downstream" dependencies.
Tool(string, [toolpath, **kw])
,
env.Tool(string, [toolpath, **kw])
The
Tool
form of the function
returns a callable object
that can be used to initialize
a construction environment using the
tools keyword of the Environment() method.
The object may be called with a construction
environment as an argument,
in which case the object will
add the necessary variables
to the construction environment
and the name of the tool will be added to the
$TOOLS
construction variable.
Additional keyword arguments are passed to the tool's
generate
()
method.
Examples:
env = Environment(tools = [ Tool('msvc') ]) env = Environment() t = Tool('msvc') t(env) # adds 'msvc' to the TOOLS variable u = Tool('opengl', toolpath = ['tools']) u(env) # adds 'opengl' to the TOOLS variable
The
env.Tool
form of the function
applies the callable object for the specified tool
string
to the environment through which the method was called.
Additional keyword arguments are passed to the tool's
generate
()
method.
env.Tool('gcc') env.Tool('opengl', toolpath = ['build/tools'])
Value(value, [built_value])
,
env.Value(value, [built_value])
Returns a Node object representing the specified Python value. Value
Nodes can be used as dependencies of targets. If the result of
calling
str
(value
)
changes between SCons runs, any targets depending on
Value
(value
)
will be rebuilt.
(This is true even when using timestamps to decide if
files are up-to-date.)
When using timestamp source signatures, Value Nodes'
timestamps are equal to the system time when the Node is created.
The returned Value Node object has a
write
()
method that can be used to "build" a Value Node
by setting a new value.
The optional
built_value
argument can be specified
when the Value Node is created
to indicate the Node should already be considered
"built."
There is a corresponding
read
()
method that will return the built value of the Node.
Examples:
env = Environment() def create(target, source, env): # A function that will write a 'prefix=$SOURCE' # string into the file name specified as the # $TARGET. f = open(str(target[0]), 'wb') f.write('prefix=' + source[0].get_contents()) # Fetch the prefix= argument, if any, from the command # line, and use /usr/local as the default. prefix = ARGUMENTS.get('prefix', '/usr/local') # Attach a .Config() builder for the above function action # to the construction environment. env['BUILDERS']['Config'] = Builder(action = create) env.Config(target = 'package-config', source = Value(prefix)) def build_value(target, source, env): # A function that "builds" a Python Value by updating # the the Python value with the contents of the file # specified as the source of the Builder call ($SOURCE). target[0].write(source[0].get_contents()) output = env.Value('before') input = env.Value('after') # Attach a .UpdateValue() builder for the above function # action to the construction environment. env['BUILDERS']['UpdateValue'] = Builder(action = build_value) env.UpdateValue(target = Value(output), source = Value(input))
VariantDir(variant_dir, src_dir, [duplicate])
,
env.VariantDir(variant_dir, src_dir, [duplicate])
Use the
VariantDir
function to create a copy of your sources in another location:
if a name under
variant_dir
is not found but exists under
src_dir
,
the file or directory is copied to
variant_dir
.
Target files can be built in a different directory
than the original sources by simply refering to the sources (and targets)
within the variant tree.
VariantDir
can be called multiple times with the same
src_dir
to set up multiple builds with different options
(variants
).
The
src_dir
location must be in or underneath the SConstruct file's directory, and
variant_dir
may not be underneath
src_dir
.
The default behavior is for
scons
to physically duplicate the source files in the variant tree.
Thus, a build performed in the variant tree is guaranteed to be identical
to a build performed in the source tree even if
intermediate source files are generated during the build,
or preprocessors or other scanners search for included files
relative to the source file,
or individual compilers or other invoked tools are hard-coded
to put derived files in the same directory as source files.
If possible on the platform,
the duplication is performed by linking rather than copying;
see also the
--duplicate
command-line option.
Moreover, only the files needed for the build are duplicated;
files and directories that are not used are not present in
variant_dir
.
Duplicating the source tree may be disabled by setting the
duplicate
argument to
0
(zero).
This will cause
scons
to invoke Builders using the path names of source files in
src_dir
and the path names of derived files within
variant_dir
.
This is always more efficient than
duplicate=1
,
and is usually safe for most builds
(but see above for cases that may cause problems).
Note that
VariantDir
works most naturally with a subsidiary SConscript file.
However, you would then call the subsidiary SConscript file
not in the source directory, but in the
variant_dir
,
regardless of the value of
duplicate
.
This is how you tell
scons
which variant of a source tree to build:
# run src/SConscript in two variant directories VariantDir('build/variant1', 'src') SConscript('build/variant1/SConscript') VariantDir('build/variant2', 'src') SConscript('build/variant2/SConscript')
See also the
SConscript
function, described above,
for another way to specify a variant directory
in conjunction with calling a subsidiary SConscript file.
Examples:
# use names in the build directory, not the source directory VariantDir('build', 'src', duplicate=0) Program('build/prog', 'build/source.c')
# this builds both the source and docs in a separate subtree VariantDir('build', '.', duplicate=0) SConscript(dirs=['build/src','build/doc'])
# same as previous example, but only uses SConscript SConscript(dirs='src', variant_dir='build/src', duplicate=0) SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)
WhereIs(program, [path, pathext, reject])
,
env.WhereIs(program, [path, pathext, reject])
Searches for the specified executable
program
,
returning the full path name to the program
if it is found,
and returning None if not.
Searches the specified
path
,
the value of the calling environment's PATH
(env['ENV']['PATH']
),
or the user's current external PATH
(os.environ['PATH']
)
by default.
On Windows systems, searches for executable
programs with any of the file extensions
listed in the specified
pathext
,
the calling environment's PATHEXT
(env['ENV']['PATHEXT']
)
or the user's current PATHEXT
(os.environ['PATHEXT']
)
by default.
Will not select any
path name or names
in the specified
reject
list, if any.