Question

I have a pure C module for Python and I’d like to be able to invoke it using the python -m modulename approach. This works fine with modules implemented in Python and one obvious workaround is to add an extra file for that purpose. However I really want to keep things to my one single distributed binary and not add a second file just for this workaround.

I don’t care how hacky the solution is.

If you do try to use a C module with -m then you get an error message No code object available for <modulename>.

Answer 1

-m implementation is in runpy._run_module_as_main . Its essence is:

mod_name, loader, code, fname = _get_module_details(mod_name)
<...>
exec code in run_globals

A compiled module has no “code object” accociated with it so the 1st statement fails with ImportError("No code object available for <module>"). You need to extend runpy – specifically, _get_module_details – to make it work for a compiled module. I suggest returning a code object constructed from the aforementioned "import mod; mod.main()":
(python 2.6.1)

    code = loader.get_code(mod_name)
    if code is None:
+       if loader.etc[2]==imp.C_EXTENSION:
+           code=compile("import %(mod)s; %(mod)s.main()"%{'mod':mod_name},"<extension loader wrapper>","exec")
+       else:
+           raise ImportError("No code object available for %s" % mod_name)
-       raise ImportError("No code object available for %s" % mod_name)
    filename = _get_filename(loader, mod_name)

(Update: fixed an error in format string)

Now…

C:\Documents and Settings\Пользователь>python -m pythoncom

C:\Documents and Settings\Пользователь>

This still won’t work for builtin modules. Again, you’ll need to invent some notion of “main code unit” for them.

Update:

I’ve looked through the internals called from _get_module_details and can say with confidence that they don’t even attempt to retrieve a code object from a module of type other than imp.PY_SOURCE, imp.PY_COMPILED or imp.PKG_DIRECTORY . So you have to patch this machinery this way or another for -m to work. Python fails before retrieving anything from your module (it doesn’t even check if the dll is a valid module) so you can’t do anything by building it in a special way.