gh-104003: Implement PEP 702 by JelleZijlstra · Pull Request #104004 · python/cpython · GitHub

Issue: Implement PEP 702: Marking deprecations using the type system #104003

This is copied from python/typing_extensions#105.

LGTM.

Waiting for the other reviewers to pipe in? This seems pretty straightforward.

Waiting for the other reviewers to pipe in? This seems pretty straightforward.

The PEP hasn't been accepted yet!

Planning to hit the merge button the moment the PEP is accepted :)

PEP 702 has been accepted, but it's changed since this PR. I'll update the PR soon to put the decorator in warnings and sync the implementation from typing-extensions.

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

Doesn't seem to be get_origin's primary use (maybe docs should be updated), but that would avoid completely refactoring the current implementation!

Doesn't seem to be get_origin's primary use

It's already sorta awkwardly overloaded in what it means tbh — the __origin__ attribute of ParamSpecArgs instances doesn't really have the same semantics as the __origin__ attribute of generic aliases :)

A class seems somewhat more elegant to me, but yeah, that would work.

I'm OK with making it a class. It's not what the object is meant for, but it's a reasonable extension.

Using __origin__ feels hacky and wouldn't provide an easy way to get the deprecation message out.

Despite static typing being the original motivation for the feature, I would actually put the runtime effect first here:

Suggested change

      
            * The new :func:`warnings.deprecated` decorator provides a way to communicate
          
              deprecations to :term:`static type checkers <static type checker>` and
          
              to warn on usage of deprecated classes and functions.
          
            * The new :func:`warnings.deprecated` decorator provides an ergonomic way to
          
              mark a class or function as deprecated. A deprecation warning will be
          
              emitted whenever a decorated function or class is used at runtime. The
          
              decorator is also understood by
          
              :term:`static type checkers <static type checker>`, which will emit warnings
          
              if they identify a decorated function or class being used.

I still want to put the type checker effect first because that's the unique part. You can write a decorator that generates runtime warnings yourself; the new and exciting part is that this decorator is also understood by static type checkers.

You can do, sure, but do people? It was possible to reimplement itertools.batched in a few lines of code before Python 3.12, but lots of people were still very excited by its inclusion in the stdlib in Python 3.12.

I think this new decorator here could prove pretty popular with people who don't use static typing! But, I don't feel strongly; it looks fine to me now :)

Sure, there are lots of third-party deprecation decorators. The Deprecated library, I think Flask has one internally (David Lord mentioned it in PEP 702 discussions), I know at Quora we have one internally.

I'm not sure if that's meant to be a point in agreement or in disagreement with the point I'm making that this decorator could prove pretty popular with people who don't use static typing. Anyway, as I say, I'm happy with the docs now!

Thanks @AlexWaygood for the review! I pushed some changes.

LGTM

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com> Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

pythongh-104003 : Implement PEP 702

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JelleZijlstra added the DO-NOT-MERGE label Apr 30, 2023

JelleZijlstra requested review from AlexWaygood, Fidget-Spinner and gvanrossum as code owners April 30, 2023 03:45

bedevere-bot mentioned this pull request Apr 30, 2023

Implement PEP 702: Marking deprecations using the type system #104003

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bedevere-bot added the awaiting core review label Apr 30, 2023

blurb

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hauntsaninja reviewed Apr 30, 2023

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Comment thread Lib/test/test_typing.py Outdated

Comment thread Lib/test/test_typing.py Outdated

Add more tests

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gvanrossum approved these changes Apr 30, 2023

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bedevere-bot added awaiting merge and removed awaiting core review labels Apr 30, 2023

JelleZijlstra added 2 commits May 6, 2023 08:30

describe runtime behavior

9b167e8

steal the typing-extensions wording instead, it's better

0ed9d41

gvanrossum approved these changes May 6, 2023

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JelleZijlstra added 4 commits November 7, 2023 19:02

Merge remote-tracking branch 'upstream/main' into pep702

2f69b4e

Put it in warnings, copy over from typing-extensions

815591b

docs

4098e62

fix test

d6625b9

JelleZijlstra removed the DO-NOT-MERGE label Nov 8, 2023

JelleZijlstra commented Nov 8, 2023

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Comment thread Doc/glossary.rst

JelleZijlstra mentioned this pull request Nov 8, 2023

Glossary: Add "static type checker" #111837

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hugovk reviewed Nov 8, 2023

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Comment thread Misc/NEWS.d/next/Library/2023-04-29-20-49-13.gh-issue-104003.-8Ruk2.rst Outdated

Update Doc/library/warnings.rst

0870a16

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

JelleZijlstra added 2 commits November 26, 2023 17:25

make it a class

ed9a10c

Merge remote-tracking branch 'upstream/main' into pep702

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AlexWaygood reviewed Nov 27, 2023

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JelleZijlstra added 5 commits November 28, 2023 18:34

Merge remote-tracking branch 'upstream/main' into pep702

e60ad5c

Forward-port typing-extensions change

d528dc8

Add test suggested by Alex

e323502

Adjust docs

acf49b3

Add to Whats New

1d663ef

JelleZijlstra added 2 commits November 28, 2023 18:44

Now that this is semi-public, use a better name

b94255d

sync docstring

e7a361b

JelleZijlstra mentioned this pull request Nov 29, 2023

Update @deprecated implementation python/typing_extensions#302

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Update error msg

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AlexWaygood reviewed Nov 29, 2023

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Apply suggestions from code review

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AlexWaygood approved these changes Nov 29, 2023

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AlexWaygood reviewed Nov 29, 2023

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Update Lib/warnings.py

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Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

JelleZijlstra merged commit d4a6229 into python:main Nov 29, 2023

bedevere-app Bot removed the awaiting merge label Nov 29, 2023

JelleZijlstra deleted the pep702 branch November 29, 2023 17:38

aisk pushed a commit to aisk/cpython that referenced this pull request Feb 11, 2024

pythongh-104003 : Implement PEP 702 (python#104004 )

81b8aeb

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com> Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

Glyphack pushed a commit to Glyphack/cpython that referenced this pull request Sep 2, 2024

pythongh-104003 : Implement PEP 702 (python#104004 )

82d9ee3

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com> Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

dolfinus mentioned this pull request Aug 22, 2025

[PROPOSAL] Add deprecation API decorator (Python) and annotation (Java) for better API lifecycle OpenLineage/OpenLineage#3984

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Viicos mentioned this pull request May 19, 2026

Clarify warnings.deprecated public API #150076

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fedonman mentioned this pull request Jul 19, 2026

gh-150076: Fix the documented signature of warnings.deprecated #153879

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gh-104003: Implement PEP 702 by JelleZijlstra · Pull Request #104004 · python/cpython · GitHub

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gh-104003: Implement PEP 702#104004JelleZijlstra merged 25 commits intopython:mainpython/cpython:mainfrom JelleZijlstra:pep702JelleZijlstra/cpython:pep702Copy head branch name to clipboard

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gh-104003: Implement PEP 702#104004
JelleZijlstra merged 25 commits into
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JelleZijlstra:pep702

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