python - collections.abc.Callable 在 Python 3.9.1 中是否被窃听？

Question

Python 3.9包括 PEP 585并弃用了 typing 中的许多类型模块支持 collections.abc 中的模块, 现在他们支持 __class_getitem__ .例如 Callable 就是这种情况。 .在我看来，typing.Callable和 collections.abc.Callable应该总是表现相似，但他们没有。
这个简单的例子会导致一个错误:

>>> from typing import Optional
>>> from collections.abc import Callable
>>> def foo(arg: Optional[Callable[[int], int]]) -> None:
...    pass
...
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/usr/local/lib/python3.9/typing.py", line 262, in inner
    return func(*args, **kwds)
  File "/usr/local/lib/python3.9/typing.py", line 339, in __getitem__
    return self._getitem(self, parameters)
  File "/usr/local/lib/python3.9/typing.py", line 463, in Optional
    return Union[arg, type(None)]
  File "/usr/local/lib/python3.9/typing.py", line 262, in inner
    return func(*args, **kwds)
  File "/usr/local/lib/python3.9/typing.py", line 339, in __getitem__
    return self._getitem(self, parameters)
  File "/usr/local/lib/python3.9/typing.py", line 451, in Union
    parameters = _remove_dups_flatten(parameters)
  File "/usr/local/lib/python3.9/typing.py", line 231, in _remove_dups_flatten
    return tuple(_deduplicate(params))
  File "/usr/local/lib/python3.9/typing.py", line 205, in _deduplicate
    all_params = set(params)
TypeError: unhashable type: 'list'

但 typing.Callable 不会发生同样的错误:

>>> from typing import Callable
>>> def foo(arg: Optional[Callable[[int], int]]) -> None:
...    pass
...
>>> # no error

如果签名稍微简化一点，也不会发生错误:

>>> from collections.abc import Callable
>>> def foo(arg: Optional[Callable[..., int]]) -> None:
...    pass
...
>>> # no error
>>> def foo(arg: Callable[[int], int]) -> None:
...    pass
...
>>> # no error

这是 Python 3.9 和 3.9.1 中的错误吗？

Answer 1

是的，collections.abc.Callable不适用于 3.9.0 和 3.9.1 中的打字目的。被举报here并固定在 3.9.2和 3.10。在此期间您可以继续使用 typing.Callable .