Do not declare Python-3-only wheels as universal

[michael-k]

Only wheels that support both Python 2 and 3 are universal. Support for Python 2 was dropped in commit 5efdd48 (part of release 2020.04.05.2).

[sigmavirus24]

Technically these wheels are universal in the sense that they run on every Python platform. There's lots of heated discussion around whether universal = true is py2 + py3 or whether it means something else and has the unfortunate side-effect of also labelling a wheel as py2 and py3.

[michael-k]

Can you point me to such a discussion? I'm only aware of the following documentation

If your project also supports Python 2 and contains no C extensions, then you should create what’s called a Universal Wheel by adding the following to your setup.cfg file:

[bdist_wheel]
universal=1

Only use this setting if your project does not have any C extesions and supports Python 2 and 3.

https://packaging.python.org/guides/distributing-packages-using-setuptools/#wheels

[graingert]

@sigmavirus24 I recently asked for clarification on this from the pyca and yes universal=0 is the preferred option for requires_python >= 3 wheels

[graingert]

pypa/packaging.python.org#726

[sigmavirus24]

If you look at pypa/twine#739 the pypa can not even agree on what universal meant when implemented versus what it means now. Further the community does not agree either. I don't think it's safe to prefer =0 strictly especially given the orthogonally implemented requires-python

[graingert]

Yeah I don't know. I prefer =1 over =0 personally

[michael-k]

Thanks for the links. Why does Python packaging have to be so complicated … :/

[sigmavirus24]

Why does Python packaging have to be so complicated … :/

Because it's founded entirely on volunteer time. Only recently has the PSF started funding/investing in packaging. Even then, 3 people can read the same specification and understand 3 different things from it. 1 may take it entirely literally, 1 may read extra into in one direction, and the third may read something else entirely different into the specification. Packaging isn't hard, humans are and it's hard to have conversations entirely over Discourse/Email/Chat that clarify these assumptions because many people aren't trained to recognize those assumptions in the moment.