[OJFord]

> The pure-Python version requires building from source and passing special flags, so it is not possible to specify it in requirements.txt.

You can put any flags in requirements.txt, including -r[equiring] another txt etc.

Your point may apply to modern pyproject.toml tooling though, or at least that it wouldn't be simply another entry in the dependencies array.

[Kwpolska]

The special flags are environment variables, you can’t pass that in requirements.txt: https://whenever.readthedocs.io/en/latest/faq.html#how-can-i...