I'm creating a setup.py
file for a project with some Cython extension modules.
I've already gotten this to work:
from setuptools import setup, Extension
from Cython.Build import cythonize
setup(
name=...,
...,
ext_modules=cythonize([ ... ]),
)
This installs fine. However, this assumes Cython is installed. What if it's not installed? I understand this is what the setup_requires
parameter is for:
from setuptools import setup, Extension
from Cython.Build import cythonize
setup(
name=...,
...,
setup_requires=['Cython'],
...,
ext_modules=cythonize([ ... ]),
)
However, if Cython isn't already installed, this will of course fail:
$ python setup.py install
Traceback (most recent call last):
File "setup.py", line 2, in <module>
from Cython.Build import cythonize
ImportError: No module named Cython.Build
What's the proper way to do this? I need to somehow import Cython
only after the setup_requires
step runs, but I need Cython
in order to specify the ext_modules
values.
Starting from 18.0 release of setuptools
(released on 2015-06-23) it is possible to specify Cython
in setup_requires
and pass *.pyx
modules sources for regular setuptools.Extension
:
from setuptools import setup, Extension
setup(
# ...
setup_requires=[
# Setuptools 18.0 properly handles Cython extensions.
'setuptools>=18.0',
'cython',
],
ext_modules=[
Extension(
'mylib',
sources=['src/mylib.pyx'],
),
],
)