There is a common set of simple tasks that many build configurations rely
on as they become more complex. Most build tools have special
purpose constructs for performing these tasks, but since &SConscript;
files are &Python; scripts, you can use more flexible built-in &Python;
services to perform these tasks. This appendix lists a number of these
tasks and how to implement them in &Python; and &SCons;.
Wildcard globbing to create a list of filenames
files = Glob(wildcard)
Filename extension substitution
import os.path
filename = os.path.splitext(filename)[0]+extension
Appending a path prefix to a list of filenames
import os.path
filenames = [os.path.join(prefix, x) for x in filenames]
Substituting a path prefix with another one
if filename.find(old_prefix) == 0:
filename = filename.replace(old_prefix, new_prefix)
Filtering a filename list to exclude/retain only a specific set
of extensions
import os.path
filenames = [x for x in filenames if os.path.splitext(x)[1] in extensions]
The "backtick function": run a shell command and capture the
output
import os
output = os.popen(command).read()
Generating source code: how code can be generated and used by SCons
The Copy builders here could be any arbitrary shell or python function
that produces one or more files. This example shows how to create
those files and use them in &SCons;.
#### SConstruct
env = Environment()
env.Append(CPPPATH = "#")
## Header example
env.Append(BUILDERS =
{'Copy1' : Builder(action = 'cat < $SOURCE > $TARGET',
suffix='.h', src_suffix='.bar')})
env.Copy1('test.bar') # produces test.h from test.bar.
env.Program('app','main.cpp') # indirectly depends on test.bar
## Source file example
env.Append(BUILDERS =
{'Copy2' : Builder(action = 'cat < $SOURCE > $TARGET',
suffix='.cpp', src_suffix='.bar2')})
foo = env.Copy2('foo.bar2') # produces foo.cpp from foo.bar2.
env.Program('app2',['main2.cpp'] + foo) # compiles main2.cpp and foo.cpp into app2.
Where main.cpp looks like this:
#include "test.h"
produces this:
% scons -Q
cc -o app main.cpp
cat < foo.bar2 > foo.cpp
cc -o app2 main2.cpp foo.cpp
cat < test.bar > test.h