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Remove ParamSpec from __parameters__ of most typing generics #88264

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Remove ParamSpec from __parameters__ of most typing generics#88264
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Fidget-Spinner
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3.10 (EOL)end of life3.11only security fixesstdlibStandard Library Python modules in the Lib/ directory

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@Fidget-Spinner
Fidget-Spinner
opened on May 10, 2021
BPO 44098
Nosy @gvanrossum, @serhiy-storchaka, @ilevkivskyi, @miss-islington, @Fidget-Spinner
PRs
  • bpo-44098: Drop ParamSpec from most __parameters__ in typing generics #26013
  • [3.10] bpo-44098: Drop ParamSpec from most __parameters__ in typing generics (GH-26013) #26091
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    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = 'https://github.com/Fidget-Spinner'
closed_at = <Date 2021-05-14.14:17:17.921>
created_at = <Date 2021-05-10.09:41:35.969>
labels = ['library', '3.10', '3.11']
title = 'Remove ParamSpec from __parameters__ of most typing generics'
updated_at = <Date 2021-07-31.13:36:10.523>
user = 'https://github.com/Fidget-Spinner'

    bugs.python.org fields:

    activity = <Date 2021-07-31.13:36:10.523>
actor = 'serhiy.storchaka'
assignee = 'kj'
closed = True
closed_date = <Date 2021-05-14.14:17:17.921>
closer = 'kj'
components = ['Library (Lib)']
creation = <Date 2021-05-10.09:41:35.969>
creator = 'kj'
dependencies = []
files = []
hgrepos = []
issue_num = 44098
keywords = ['patch']
message_count = 8.0
messages = ['393373', '393589', '393662', '398283', '398300', '398346', '398393', '398641']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'serhiy.storchaka', 'levkivskyi', 'miss-islington', 'kj']
pr_nums = ['26013', '26091']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue44098'
versions = ['Python 3.10', 'Python 3.11']

    Activity

    1. Fidget-Spinner commented on May 10, 2021

      @Fidget-Spinner
      Fidget-Spinner
      on May 10, 2021
      MemberAuthor

      typing.List includes ParamSpec in __parameters__ but the builtin list doesn't. The behavior of the latter is correct, as PEP-612 states that: "As before, parameters_expressions by themselves are not acceptable in places where a type is expected".

      https://www.python.org/dev/peps/pep-0612/#valid-use-locations

      This patch just makes the typing version same as the builtin version by excluding ParamSpec from __parameters__ (except for Concatenate, Callable, and Generic).

    2. Fidget-Spinner
      added
      3.10 (EOL)end of life
      3.11only security fixes
      on May 10, 2021
    3. Fidget-Spinner
      self-assigned this
      on May 10, 2021
    4. Fidget-Spinner
      added
      stdlibStandard Library Python modules in the Lib/ directory
      3.10 (EOL)end of life
      3.11only security fixes
      on May 10, 2021
    5. Fidget-Spinner
      self-assigned this
      on May 10, 2021
    6. Fidget-Spinner
      added
      stdlibStandard Library Python modules in the Lib/ directory
      on May 10, 2021

    7. gvanrossum commented on May 13, 2021

      @gvanrossum
      gvanrossum
      on May 13, 2021
      Member

      New changeset c55ff1b by Miss Islington (bot) in branch '3.10':
      bpo-44098: Drop ParamSpec from most __parameters__ in typing generics (GH-26013) (bpo-26091)
      c55ff1b

    8. Fidget-Spinner commented on May 14, 2021

      @Fidget-Spinner
      Fidget-Spinner
      on May 14, 2021
      MemberAuthor

      All patches have landed. Thanks Guido!

    9. Fidget-Spinner
      closed this as completedon May 14, 2021
    10. Fidget-Spinner
      closed this as completedon May 14, 2021

    11. serhiy-storchaka commented on Jul 27, 2021

      @serhiy-storchaka
      serhiy-storchaka
      on Jul 27, 2021
      Member

      I think that List[P] should be illegal at first place.

    12. gvanrossum commented on Jul 27, 2021

      @gvanrossum
      gvanrossum
      on Jul 27, 2021
      Member

      Yeah, but we shouldn't go out of our way to reject it. Especially since in 3.11 we'll likely have something equivalent to PEP-563 or PEP-649 (the SC is thinking deep about this right now) and either of those means that usually it won't be evaluated at all anyway (you'd have to call get_type_hints() with PEP-563, or use __annotations__ with the other).

    13. serhiy-storchaka commented on Jul 28, 2021

      @serhiy-storchaka
      serhiy-storchaka
      on Jul 28, 2021
      Member

      I am writing a patch which generalizes and significantly simplifies the code for type variables and parameter specifications substitution, and opens a way for more runtime validation. But it is incompatible with these changes.

    14. Fidget-Spinner commented on Jul 28, 2021

      @Fidget-Spinner
      Fidget-Spinner
      on Jul 28, 2021
      MemberAuthor

      @serhiy, could you please briefly describe what you are planning? I'm guessing you're generalizing for _TypeVarLike?

      My main concern is that we should have as few differences between builtin and typing types as possible. typing.List is deprecated and set to remove in Python 3.13/14, so I'm hoping the transition will be fairly painless.

      Originally, the builtin types supported ParamSpec, but I removed that in #69635 for various reasons listed in that PR.

    15. serhiy-storchaka commented on Jul 31, 2021

      @serhiy-storchaka
      serhiy-storchaka
      on Jul 31, 2021
      Member

      See bpo-44796.

    16. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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