Currently typing functions get_origin(), get_args() and get_type_hints() do not support GenericAlias.

>>> from typing import *
>>> get_origin(List[int])
<class 'list'>
>>> get_origin(list[int])
>>> get_args(List[int])
(<class 'int'>,)
>>> get_args(list[int])
()
>>> def foo(x: List[ForwardRef('X')], y: list[ForwardRef('X')]) -> None: ...                                                                                                                                                                 
...                                                                                                                                                                                                                                          
>>> class X: ...
... 
>>> get_type_hints(foo)
{'x': typing.List[__main__.X], 'y': list[ForwardRef('X')], 'return': <class 'NoneType'>}

The proposed PR fixes this.

New changeset 68b352a by Serhiy Storchaka in branch 'master':
bpo-40396: Support GenericAlias in the typing functions. (GH-19718)
68b352a

@serhiy-storchaka
why does get_origin(list) returns None while get_origin(List) returns <class 'list'>

shouldn't list behaves exactly the same as List? (the same question applies to all generics)

@danielkatzan Looks like an omission in the code for get_origin(). Would you like to submit a PR to fix it? I can't promise that it will make it into 3.11 but it will be in 3.11.1.

@gvanrossum Sure, I would be happy to, but could use a little pointer here
Not sure how this can be accomplished

note while type(list[str]) is <class 'types.GenericAlias'> and has the __origin__ attribute, type(list) is actually <class 'type'> and doesn't have an __origin__ attribute

I can add an explicit if, checking if the tp is actually dict\list etc, and return that instead of None

will that be a valid approach? or just masking a deeper issue that might pop up later in a different location?

This issue was closed 2 years ago, please open a new issue.

The fact that get_origin(List) returns list is not documented. It looks to me like an implementation artifact.

The fact that get_origin(List) returns list is not documented. It looks to me like an implementation artifact.

Changing that would be a breaking change at this point (at least... it would break code that I, personally, have written).

opened this #95539