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Title: [typing] Runtime protocols with ClassVar data members should support issubclass
Type: enhancement Stage: patch review
Components: Library (Lib) Versions: Python 3.11
Status: open Resolution:
Dependencies: Superseder:
Assigned To: kj Nosy List: JelleZijlstra, gvanrossum, kj
Priority: normal Keywords: patch

Created on 2021-08-22 08:56 by kj, last changed 2022-04-11 14:59 by admin.

Pull Requests
URL Status Linked Edit
PR 27883 open kj, 2021-08-22 09:01
Messages (2)
msg400059 - (view) Author: Ken Jin (kj) * (Python committer) Date: 2021-08-22 08:56
This is a feature request by a user at

A copy of their request:
Currently issubclass cannot be used for runtime_checkable protocols with data members, because those attributes could be set in __init__. I propose to relax this restriction to allow protocols with ClassVar members, as those should be present in the class definition.

I'm unsure if I need to update PEP 544 too. I don't remember if PEPs can be updated when 'Accepted', or was it 'Final' PEPs that can't be updated anymore?
msg411184 - (view) Author: Guido van Rossum (gvanrossum) * (Python committer) Date: 2022-01-21 21:12
IMO we shouldn't update PEP 544. PEPs reflect the historical proposal, they are not documentation for the current state of the interpreter.
Date User Action Args
2022-04-11 14:59:49adminsetgithub: 89138
2022-01-21 21:12:18gvanrossumsetmessages: + msg411184
2021-08-22 09:01:24kjsetkeywords: + patch
stage: patch review
pull_requests: + pull_request26338
2021-08-22 08:56:49kjcreate