> setuptools will detect at build time whether Cython is installed or not. If Cython is not found setuptools will ignore pyx files.
> To ensure Cython is available, include Cython in the build-requires section of your pyproject.toml:
[build-system]
requires=[..., "cython"]
> Built with pip 10 or later, that declaration is sufficient to include Cython in the build. For broader compatibility, declare the dependency in your setup-requires of setup.cfg:
Is it possible for Cython? Their guide shows using setup.py:
https://cython.readthedocs.io/en/latest/src/tutorial/cython_...