Cythonization of a pure Python package in setup.py

setup.py

# Run me with:
# python3 setup.py bdist_wheel --cythonize

# ...

if '--cythonize' in argv:
    from Cython.Build import cythonize
    packaging = {
        'ext_modules': cythonize('lib/**/*.py'),
    }
    argv.remove('--cythonize')
else:
    packaging = {
        'package_dir': {'': 'lib'},
        'packages': find_packages('lib'),
    }

setup(
    # ....
    **packaging
)