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7.3 Single extension module

Extension modules are specified using the ext_modules option. package_dir has no effect on where extension source files are found; it only affects the source for pure Python modules. The simplest case, a single extension module in a single C source file, is:

    <root>/
            setup.py
            foo.c

If the `foo` extension belongs in the root package, the setup script for this could be

    from distutils.core import setup
    setup(name='foobar',
          version='1.0',
          ext_modules=[Extension('foo', ['foo.c'])],
          )

If the extension actually belongs in a package, say `foopkg`, then

With exactly the same source tree layout, this extension can be put in the `foopkg` package simply by changing the name of the extension:

    from distutils.core import setup
    setup(name='foobar',
          version='1.0',
          ext_modules=[Extension('foopkg.foo', ['foo.c'])],
          )