December 14th 2007 11:52 am
Creating a Python module with Scons and SWIG
Some times ago, I proposed an optional build for SWIG if the SWIG binary was not found on the system. Here I propose an enhancement, a new library builder that will be registered in the environment env as PythonModule. It takes the same arguments as a classical SharedLibrary, but it does some additional steps :
- It forces SWIG to create a Python wrapper (flag -python)
- It checks if SWIG is present at all
- It suppresses every prefix that the system might need (as lib in Linux)
- On Windows and for Python >= 2.5, it changes the extension as pyd
Here is the code :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | import re import sys def SWIGSharedLibrary(env, library, sources, **args): swigre = re.compile('(.*).i') if env.WhereIs('swig') is None: sourcesbis = [] for source in sources: cName = swigre.sub(r'\1_wrap.c', source) cppName = swigre.sub(r'\1_wrap.cc', source) if os.path.exists(cName): sourcesbis.append(cName) elif os.path.exists(cppName): sourcesbis.append(cppName) else: sourcesbis.append(source) else: sourcesbis = sources if 'SWIGFLAGS' in args: args['SWIGFLAGS'] += ['-python'] else: args['SWIGFLAGS'] = ['-python'] + env['SWIGFLAGS'] args['SHLIBPREFIX']="" if sys.version >= '2.5': args['SHLIBSUFFIX']=".pyd" cat=env.SharedLibrary(library, sourcesbis, **args) return cat env['BUILDERS']['PythonModule'] = SWIGSharedLibrary |
Once registered, a new SWIG module named mymodule can be created with :
env.PythonModule('_mymodule', ['myfile.i', 'myfile.c']) |
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2 Responses to “Creating a Python module with Scons and SWIG”
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Mark Gritter on 25 Jun 2008 at 3:44 am #
I’m a bit confused at registering a python function directly as a Builder, instead of creating a custom Builder with an action or generator. I’d like to do something similar (so I can use other builders like you use env.SharedLibrary), but I’m not sure this is a supported usage… What exactly goes on here?
Matt on 25 Jun 2008 at 6:58 am #
In fact, the real builder is still SharedLibrary for SCons. What I do is preprocess the sources in case SWIG is not available (I change .i for _wrap.c or _wrap.cc), and then I add ‘-python’ so that swig really understands it has to create a Python module. Finally, I change the library suffix and prefix if needed before I call the real builder, SharedLibrary.