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1. Daraan commented on Sep 3, 2025

   

   Daraan

   on Sep 3, 2025

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   The assertions you listed differ in both cases. I would think one wants the same code in both cases?
   (str, int) is the current behavior on Python 3.13 / 3.14.

   Under typing_extensions 4.14.1 it returns only (str,) with 4.15.0 it also returns the default value similar to 3.13 typing.

   To my knowledge it is the intended behavior to get the all arguments get_args with defaults substituted in.
2. brianschubert commented on Sep 3, 2025

   

   brianschubert

   on Sep 3, 2025

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   This only seems to affect typing_extensions on Python 3.9 and 3.10. This script:

   from typing_extensions import TypeVar, Generic, get_args
   R = TypeVar("R")
   T = TypeVar("T", default=int)
   class A(Generic[R, T]): ...
   
   print(f"{get_args(A[str])=}    {A[str].__args__=}")

   produces:

   $ uv run --python 3.11 temp.py
   get_args(A[str])=(<class 'str'>, <class 'int'>)    A[str].__args__=(<class 'str'>, <class 'int'>)
   
   $ uv run --python 3.10 temp.py
   get_args(A[str])=(<class 'str'>,)    A[str].__args__=(<class 'str'>,)

   Based on a cursor look with a debugger, the behavior difference comes from inside Generic.__class_getitem__. Fixing this might require monkey patching it on Python 3.9 & 3.10
3. IvanKirpichnikov commented on Sep 4, 2025

   

   IvanKirpichnikov

   on Sep 4, 2025

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   I think we don't need monkey pathing here. It is enough to write your own Generic object that will be able to use TypeVar defaults

   At the moment, typing_extensions uses the mechanism of re-exporting the Generic class from the original typing package
4. IvanKirpichnikov commented on Sep 13, 2025

   

   IvanKirpichnikov

   on Sep 13, 2025

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   Is there any news on this bug? Should I send a pull request with a bug fix?
5. jacksonthall22 commented on Oct 9, 2025

   

   jacksonthall22

   on Oct 9, 2025

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   MRE with the new generics syntax:

   # temp.py
   from typing_extensions import get_args
   
   
   class Foo[T = str]:
       x: T
   
   f = Foo()
   
   try:
       reveal_type(f.x)
   except NameError:
       pass
   
   print(get_args(f))

   $ mypy temp.py 
   temp.py:9: note: Revealed type is "builtins.str"
   Success: no issues found in 1 source file
   $ python temp.py
   ()
6. JelleZijlstra commented on Oct 10, 2025

   

   JelleZijlstra

   on Oct 10, 2025

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   @jacksonthall22 that's unrelated (your example doesn't involve typing-extensions). You need to call get_args() on the class, not an instance.

   @IvanKirpichnikov PRs welcome! We'll have to see how invasive the fix is; it only affects 3.9 (which is about to go EOL) and 3.10 (which is also getting towards the end of its support).

   👀React with 👀1Reacted by Jackson Hall
7. IvanKirpichnikov commented on Oct 11, 2025

   

   IvanKirpichnikov

   on Oct 11, 2025

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   @IvanKirpichnikov PRs welcome! We'll have to see how invasive the fix is; it only affects 3.9 (which is about to go EOL) and 3.10 (which is also getting towards the end of its support).

   I didn't understand the argument about 3.10. Type var defaults appeared in 3.13.
   That is, you need to make your typing_extensions.Generic to EOL 3.13. No?
8. JelleZijlstra commented on Oct 11, 2025

   

   JelleZijlstra

   on Oct 11, 2025

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   If I understand the previous discussion correctly, this bug appears only in 3.9 and 3.10. If it instead appears up to 3.12, that does make it more important to fix.
9. IvanKirpichnikov commented on Oct 11, 2025

   

   IvanKirpichnikov

   on Oct 11, 2025

   Last edited by IvanKirpichnikov

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   It appears on versions <3.13(that is 3.10, 3.11, 3.12) because typing_extensions.Generic is literally typing.Generic

   I think this option is critical because it requires working with default value options in input extensions.
10. JelleZijlstra commented on Oct 11, 2025

    

    JelleZijlstra

    on Oct 11, 2025

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    On Python 3.11 and 3.12 with typing-extensions, get_args() returns the same thing as on 3.13+ with typing (as @brianschubert reported a few comments up). If you think something is still wrong on 3.11 and 3.12, please report exactly what you expect to happen and what is happening instead.

    because typing_extensions.Generic is literally typing.Generic

    That's an implementation detail; we don't necessarily have to duplicate Generic itself to solve this issue. We care only about the publicly visible behavior.