Ken Jin <kenjin4...@gmail.com> added the comment:
@eric.smith, here's a summarized version. I hope it helps: def foo(x: str) -> str: ... In Python 3.7 - 3.9 with from __future__ import annotations, inspect.signature sees foo's parameter as: <Parameter "x: 'str'"> Without the future import (and also in Python 3.10): <Parameter "x: str"> The reason for the difference in 3.10 (IIRC) is that inspect.signature auto converts all strings to typing.ForwardRef internally and then resolves them. This is a result of PEP 563 becoming default (also mentioned here https://docs.python.org/3.10/whatsnew/3.10.html#pep-563-postponed-evaluation-of-annotations-becomes-default ) Prior to 3.10, the future import treats function annotations as strings and inspect.signature _doesn't_ convert them. I don't know of this is a bug or intentional. Especially considering what PEP 563 has to say: https://www.python.org/dev/peps/pep-0563/#resolving-type-hints-at-runtime @1ace, a possible workaround if you want full compatibility regardless of the future import is to use typing.get_type_hints: (The result doesn't change even with from __future__ import annotations. This also works from 3.7-3.10) >>> from typing import get_type_hints >>> get_type_hints(foo) {'x': <class 'str'>, 'return': <class 'str'>} ---------- nosy: +kj _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue43355> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
