The function presented here is useful if:
- You've got one environment used to create many targets (too many to start messing with).
- The environment is configured differently for different platforms/compilers/etc.
- Some platforms/compilers/etc. need an additional source file to be compiled in order to work properly. This can be, for example, a replacement for a library that is not available on a certain platform. This function wraps a given emitter with another emitter that adds another file to the source nodes.
Replaceable emitters (as of SCons 0.96.90):
PROGEMITTER- emitter for Program builder
SHLIBEMITTER- emitter for SharedLibrary builder
LIBEMITTER- emitter for Library builder
#!python def add_file_to_emitter(env, emitter_name, file): try: original_emitter = env[emitter_name] if type(original_emitter) == list: original_emitter = original_emitter except KeyError: original_emitter = None def emitter(target, source, env): if original_emitter: target, source = original_emitter(target, source, env) return target, source + [file] env[emitter_name] = emitter
In this example, the environment is searched for a library called somelib. If this library is not found, add_file_to_emitter is called to add somelibreplacement.c to every program built using the environment.
#!python env = Environment() conf = env.Configure() if not conf.CheckLib('somelib'): add_file_to_emitter(env, 'PROGEMITTER', File('somelibreplacement.c')) conf.Finish()
- -- AmirSzekely
Changing the Emitter for StaticObject
If you want to change where a builder finds its C/C++ source files, you want to change the emitter for the StaticObject builder, aka Object. Unfortunately, there is no OBJEMITTER currently defined, but another way to do it is shown below.
#!python # Assuming the BUILD_DIR is set to the location of the generated files # and some other generated files are in OTHER_BUILD_DIR def my_emitter(target, source, env): ''' Tell SCons about the locations of some generated files. This could be any emitter you want''' if os.path.exists(source.path): # The source file was generated in the local build directory return (target, source) altSrcName = source.abspath.replace(env['BUILD_DIR'] + os.sep, '') if os.path.exists(altSrcName): # The source file is in the source directory return (target, altSrcName) # Assume that the source file is in the other generated files build directory altSrcName = "%s/%s%s" % (File('#'), env['OTHER_BUILD_DIR'], source.path.replace(env['OTHER_BUILD_DIR'], '')) return (target, altSrcName) # This is the part where we override the emitter for the Object builder from SCons.Tool import createObjBuilders # Get the underlying builder objects static_obj, shared_obj = createObjBuilders(env) # Now SCons can find .cpp files in different locations static_obj.add_emitter('.cpp', my_emitter)
- -- MattDoar