Deprecate keyword args syntax for TypedDict definition

@gvanrossum

BPO	46066
Nosy	@gvanrossum, @JelleZijlstra, @tirkarthi, @sobolevn, @Fidget-Spinner, @AlexWaygood, @97littleleaf11
PRs	bpo-46066: Deprecate kwargs syntax for TypedDict definitions #31126 bpo-46066: catch DeprecationWarning #31428

^{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 = None
closed_at = <Date 2022-02-17.03:26:40.796>
created_at = <Date 2021-12-13.15:36:57.408>
labels = ['type-bug', 'library', '3.11']
title = 'Deprecate keyword args syntax for TypedDict definition'
updated_at = <Date 2022-02-20.01:44:58.632>
user = 'https://github.com/97littleleaf11'

bugs.python.org fields:

activity = <Date 2022-02-20.01:44:58.632>
actor = 'JelleZijlstra'
assignee = 'none'
closed = True
closed_date = <Date 2022-02-17.03:26:40.796>
closer = 'JelleZijlstra'
components = ['Library (Lib)']
creation = <Date 2021-12-13.15:36:57.408>
creator = '97littleleaf11'
dependencies = []
files = []
hgrepos = []
issue_num = 46066
keywords = ['patch']
message_count = 11.0
messages = ['408458', '408476', '408547', '412990', '413013', '413014', '413016', '413379', '413531', '413535', '413562']
nosy_count = 7.0
nosy_names = ['gvanrossum', 'JelleZijlstra', 'xtreak', 'sobolevn', 'kj', 'AlexWaygood', '97littleleaf11']
pr_nums = ['31126', '31428']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue46066'
versions = ['Python 3.11']

According to the docs: https://docs.python.org/3/library/typing.html?#typing.TypedDict, there are two additional equivalent syntax for TypedDict definition.

Point2D = TypedDict('Point2D', x=int, y=int, label=str)
Point2D = TypedDict('Point2D', {'x': int, 'y': int, 'label': str})

However, the former one is quite confusing since we have the total keyword arg for TypedDict. In addition, PEP-589(https://www.python.org/dev/peps/pep-0589/#id19) doesn't have this.

I think we could discard the definition syntax using keyword args in the doc.

This is not really just a doc issue then, is it? Maybe we should just deprecate the feature?

Just so that all the discussion related to this issue can be found in one place, here's a summary:

After opening this ticket, OP opened an issue in the python/typing repository, where the idea of deprecating this syntax received many thumbs-up reactions, and where there were no dissenting voices: TypedDict alternative definition syntax with keyword args is confusing typing#981
The initial impetus for this change was this mypy bug report: TypedDict using keywords causes "error: Too many arguments for TypedDict()" mypy#11555
Mypy's policy since January 2020 has been that it would be more trouble than it's worth to attempt to support the kwargs-based syntax: TypedDict syntax variant with keyword arguments mypy#2492 (comment)

Go ahead and send a or to deprecate it.--
--Guido (mobile)

"PR"

@guido

@guido, OP already has — Jelle and I have both reviewed and approved it :)

New changeset de6043e by 97littleleaf11 in branch 'main':
bpo-46066: Deprecate kwargs syntax for TypedDict definitions (GH-31126)
de6043e

This change has introduced deprecation warning in tests

PYTHONWARNINGS=always ./python -Wall -X dev -m test.test_typing     
........................................................................................................................................................................................................................s................................................................................................................................................................................................./home/karthikeyan/stuff/python/cpython/Lib/test/test_typing.py:4589: DeprecationWarning: The kwargs-based syntax for TypedDict definitions is deprecated in Python 3.11, will be removed in Python 3.13, and may not be understood by third-party type checkers.
  TypedDict('Emp', _fields={'name': str, 'id': int})
./home/karthikeyan/stuff/python/cpython/Lib/test/test_typing.py:4602: DeprecationWarning: The kwargs-based syntax for TypedDict definitions is deprecated in Python 3.11, will be removed in Python 3.13, and may not be understood by third-party type checkers.
  TypedDict('Hi', x=1)
........................................

Ran 451 tests in 0.105s

OK (skipped=1)

Thanks, I'll send a PR.

New changeset 0a8a8e7 by Jelle Zijlstra in branch 'main':
bpo-46066: Check DeprecationWarning in test_typing (GH-31428)
0a8a8e7

@labrys

@labrys

Doesn't this cause issues for keys that are valid as keys but not as identifiers?

To the contrary, the deprecated syntax caused issues for such keys. The syntax that isn't deprecated works fine, e.g.

Point2D = TypedDict('Point2D', {'x': int, 'y': int, '$label$': str})

@gvanrossum

@gvanrossum Thanks for the quick response. I deleted my previous comment right after I posted it realizing I had entirely misread it as if the kwargs method was the one being retained.

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Deprecate keyword args syntax for TypedDict definition #90224

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Deprecate keyword args syntax for TypedDict definition #90224

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97littleleaf11 commented on Dec 13, 2021

gvanrossum commented on Dec 13, 2021

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AlexWaygood commented on Feb 10, 2022

gvanrossum commented on Feb 10, 2022

gvanrossum commented on Feb 10, 2022

AlexWaygood commented on Feb 10, 2022

JelleZijlstra commented on Feb 17, 2022

tirkarthi commented on Feb 19, 2022

JelleZijlstra commented on Feb 19, 2022

JelleZijlstra commented on Feb 20, 2022

gvanrossum commented on Dec 22, 2022

labrys commented on Dec 22, 2022

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