Ideally this problem should be solved with the Provides-Dist metadata.[1] The exact semantic to the flag is unfortunately not discussed much currently, and no installer implementations that I know of (including pip) support it at all. This also recently came up in pip’s issue tracker,[2] and I guess this is as good a time as any to start the conversation if someone is willing to help drive that discussion forward. [1]: https://packaging.python.org/specifications/core-metadata/#provides-dist-mul... [2]: https://github.com/pypa/pip/issues/8669 -- Tzu-ping Chung (@uranusjr) uranusjr@gmail.com https://uranusjr.com

On 03/8, 2020, at 05:59, Daniele Varrazzo wrote:

On Sun, 2 Aug 2020 at 21:34, Bert JW Regeer wrote:

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By splitting it into two different packages you end up with the same situation that currently plagues psycopg2/psycopg2-binary whereby if you depend on psycopg2 you can't easily swap in psycopg2-binary and vice-versa as the two don't satisfy the same dependency.

The psycopg2 wheel or not wheel is the situation you describe, and it's really suboptimal from the point of declaring dependencies: beginners would like to use psycopg2-binary, but projects are advised to depend on psycopg2, so they either don't get the wheel benefit or they end up in a tangle of dependencies, two distributions installing the same files, bad stuff. Offering the C distribution as an opt-in extension would allow projects to depend only on the pure python psycopg3, which would be also the right choice for beginners, and allowing the grown-ups with a compiler to go faster by installing psycopg3-c too, which wouldn't conflict with the basic package.

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Number 3 is kind of what sqlalchemy does, and then provide wheels for a huge variety of platforms to allow people to install the package without needing a compiler themselves.

The difference in performance of the C extension is important enough (15-20x - https://www.varrazzo.com/blog/2020/05/19/a-trip-into-optimisation/) to arguably make or break a deal. If someone wanted the C extension because they need the performance I wouldn't want its installation to fail silently.

-- Daniele -- Distutils-SIG mailing list -- distutils-sig@python.org To unsubscribe send an email to distutils-sig-leave@python.org https://mail.python.org/mailman3/lists/distutils-sig.python.org/ Message archived at https://mail.python.org/archives/list/distutils-sig@python.org/message/MQNGT...