collections.abc.Callable 在 Python 3.9.1 中有问题吗？

Question

Python 3.9 includes PEP 585 and deprecates many of the types in the typing module in favor of the ones in collections.abc, now that they support __class_getitem__. This is the case with for example Callable。在我看来，typing.Callable 和 collections.abc.Callable 的行为应该总是相似的，但事实并非如此。

这个简单的例子导致错误：

>>> 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'

但是 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

签名稍微简化一点也不会出现这个错误:

>>> 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 中的键入目的。据报道here and is fixed in 3.9.2和3.10。在此期间您可以继续使用 typing.Callable.

collections.abc.Callable 在 Python 3.9.1 中有问题吗？

Is collections.abc.Callable bugged in Python 3.9.1?

python

python-3.x

python-collections

python-typing

python-3.9