[issue42195] Inconsistent __args__ between typing.Callable and collections.abc.Callable

[Shantanu]

Shantanu <hauntsaninja at gmail.com> added the comment:

You're right that Callable[[P], int] is invalid, so a flat representation isn't currently ambiguous. But a flat representation would foist the responsibility for checking that to all users of `__args__`. If your code isn't ParamSpec aware, your failures will probably be less obvious or even silent.

The flat representation trades off a) implementation complexity with b) usability / aesthetics, c) future proof-ness. I'm not morally opposed to such a tradeoff / am happy to defer to people with more experience in making such tradeoffs.

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue42195>
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