Paramspec cannot be used as tuple/dict #12386

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1. kasium

   added

   bugmypy got something wrongmypy got something wrong

   on Mar 19, 2022
2. JelleZijlstra

   added

   topic-paramspecPEP 612, ParamSpec, ConcatenatePEP 612, ParamSpec, Concatenate

   on Mar 19, 2022
3. AlexWaygood commented on Apr 24, 2022

   

   AlexWaygood

   on Apr 24, 2022

   Last edited by AlexWaygood

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   I just closed #12660 as a duplicate. Here's the repro from that issue, by @rbroderi:

   from typing import TypeVar, Callable, ParamSpec
   from functools import wraps
   
   P = ParamSpec("P")
   R = TypeVar("R")
   
   def dec_test(func: Callable[P, R]) -> Callable[P, R]:
       @wraps(func)
       def inner(*args: P.args, **kwargs: P.kwargs) -> R:
           for a in args:  # error: "P.args" has no attribute "__iter__" (not iterable)
               print(a)
           for arg_k, arg_v in kwargs.items():  # error: "P.kwargs" has no attribute "items"
               print(f"{arg_k},{arg_v}")
           return func(*args, **kwargs)
     
       return inner

   Playground link: https://mypy-play.net/?mypy=latest&python=3.10&gist=52d9dbf3999e25e8a72c3bb20c1cb097
4. JukkaL

   closed this as completedin #12668on Apr 29, 2022
5. JukkaL

   added a commit that references this issue on Apr 29, 2022

   Use tuple[object, ...] and dict[str, object] as upper bounds for Para…

   ...

   This issue will close once commit c6cf7cd is merged into the 'master' branch.

   c6cf7cd
6. svenpanne commented on Aug 23, 2022

   

   svenpanne

   on Aug 23, 2022

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   I don't think that this is fully fixed, a slight variation using destructuring doesn't work:

   from collections.abc import Callable
   from typing import ParamSpec
   
   P = ParamSpec("P")
   
   def foo(func: Callable[P, None]) -> None:
       def _inner(*args: P.args, **kwargs: P.kwargs) -> None:
           x, *y = args

   See https://mypy-play.net/?mypy=latest&python=3.10&gist=0c605f87eb31c12b25c7da8f7c2819cd. You get the error: main.py:8: error: "P.args" object is not iterable. The really funny thing is that looping with for x in args works. Can you re-open this ticket?
7. AlexWaygood commented on Aug 23, 2022

   

   AlexWaygood

   on Aug 23, 2022

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   @svenpanne, I fixed that just the other day in #13459. It'll be included in the next mypy release (0.980).

   👍React with 👍1Reacted by Sven Panne