New submission from Zac Hatfield-Dodds <zac.hatfield.do...@gmail.com>:
The two ways of getting a parametrised Callable have inconsistent __args__:
>>> import collections.abc, typing
>>> typing.Callable[[int, int], int].__args__
(int, int, int)
>>> collections.abc.Callable[[int, int], int].__args__
([int, int], int)
I discovered this while working on PEP 585 support in Hypothesis [1], where it
is easy enough to work around but carries a potentially serious performance
cost - the list means we cannot use the type as a cache key for non-`...`
argument types.
https://bugs.python.org/issue40494 and https://bugs.python.org/issue40398 may
be related.
[1] https://github.com/HypothesisWorks/hypothesis/pull/2653
----------
components: Library (Lib)
messages: 379869
nosy: Zac Hatfield-Dodds, gvanrossum, levkivskyi, serhiy.storchaka
priority: normal
severity: normal
status: open
title: Inconsistent __args__ between typing.Callable and
collections.abc.Callable
type: behavior
versions: Python 3.10, Python 3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue42195>
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