问用cython创建包，这样用户就可以安装它，而不必安装cython。

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import os
from glob import glob
from distutils.command.build_ext import build_ext as _build_ext
from distutils.command.sdist import sdist as _sdist
from distutils.core import setup
from distutils.core import Extension



def generate_extensions():
    return [
        # Compile cython-generated .c files into importable .so libraries.
        Extension(os.path.splitext(name)[0], [name])
        for name in C_FILES
    ]


# In distribution version, there are no pyx files, when you clone package from git, there will be no c files.
CYTHON_FILES = glob('itchy/*.pyx')
C_FILES = glob('itchy/*.c')
extensions = generate_extensions()


class build_ext(_build_ext):
    def run(self):
        # Compile cython files (.pyx, some of the .py) into .c files if Cython is available.
        try:
            from Cython.Build import cythonize
            if CYTHON_FILES:
                cythonize(CYTHON_FILES)

                # Update C_FILES in case they were originally missing.
                global C_FILES, extensions
                C_FILES = glob('itchy/*.c')
                extensions = generate_extensions()
            else:
                print('No .pyx files found, building extensions skipped. Pre-built versions will be used.')
        except ImportError:
            print('Cython is not installed, building extensions skipped. Pre-built versions will be used.')
            assert C_FILES, 'C files have to be present in distribution or Cython has to be installed'
        _build_ext.run(self)


class sdist(_sdist):
    def run(self):
        # Make sure the compiled Cython files in the distribution are up-to-date
        self.run_command("build_ext")
        _sdist.run(self)


setup(
    (...)
    ext_modules = extensions,
    cmdclass = {
        'build_ext': build_ext,
        'sdist': sdist,
    },
)