Although SCons provides many useful methods
for building common software products:
programs, libraries, documents.
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 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.