[Python-Dev] PEP 575, 576, 579 and 580 (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Sat Jul 7 10:50:58 EDT 2018

On Sun, 8 Jul 2018 00:14:13 +1000 Nick Coghlan <ncoghlan at gmail.com> wrote:

> So, let us gather the requirements for a new calling API. > Here are my starting suggestions: > > 1. The new API should be fully backwards compatible and shouldn't break the > ABI > 2. The new API should be used internally so that 3rd party extensions are > not second class citizens in term of call performance. > 3. The new API should not prevent 3rd party extensions having full > introspection capabilities, supporting keyword arguments or another feature > supported by Python functions. > 4. The implementation should not exceed D lines of code delta and T lines of > code in total size. I would suggest +200 and 1000 for D and T respectively > (or is that too restrictive?). > 5. It should speed up CPython for the standard benchmark suite. > 6. It should be understandable. I like points 1, 2, 3, and 6, but I think point 4 should be a design trade-off rather than a requirement, since minimising the delta in CPython becomes an anti-goal if the outcome of doing so is to make the change harder to adopt for third party projects (at the same time, a delta that's too large is unlikely to be accepted, reviewed and merged, which is what makes it a trade-off). I don't think point 5 is a goal here either, as the problem isn't that these calling optimisations don't exist, it's that they don't currently have a public API that third party projects can access (the most recent METHFASTCALL thread covers that pretty well).

Agreed. The goal is not to speed up CPython but to bring third-party extensions up to speed (both literally and figuratively).

Regards

Antoine.

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