Build a package with cython so that users can install it without installing the already installed cython

Question

I have a question. I would like to distribute my packages based on cython, but I do not see an easy way to create them in the setup.py file. I would like to setup.py for:

• Most important: install my package without cython (from pre-generated C files or by installing cython in advance)
• rebuild (run cythonize) package on sdist
• don't need a list of hard codes of my cython modules (just use glob or something else)
• be able to work without .c files (should not be stored in git) or .pyx (may not be distributed). at least one of these sets will always be present, of course.

Currently, in my buttock package I use this rather complex code:

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,
    },
)

Answer 1

cython

• pyx cython, cython
• C, cython

:

try:
    from Cython.Distutils.extension import Extension
    from Cython.Distutils import build_ext
except ImportError:
    from setuptools import Extension
    USING_CYTHON = False
else:
    USING_CYTHON = True

ext = 'pyx' if USING_CYTHON else 'c'
sources = glob('my_module/*.%s' % (ext,))
extensions = [
    Extension(source.split('.')[0].replace(os.path.sep, '.'),
              sources=[source],
    )
for source in sources]
cmdclass = {'build_ext': build_ext} if USING_CYTHON else {}

setup(<..>, ext_modules=extensions, cmdclass=cmdclass)

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