gh-100458: Clarify Enum.format() change of mixed-in types in the whatsnew/3.11.rst#100387

anze3db

Hey! 👋

Please correct me if I'm wrong, but the description of the change Enum.format() change in 3.11.rst doesn't seem accurate. The behavior in older Python versions was to return the member's value and not the member's key as is currently stated. Example code:

from enum import Enum


class Foo(str, Enum):
    BAR = "baz"


print("{}".format(Foo.BAR))


class Foo(int, Enum):
    BAR = 1


print("{}".format(Foo.BAR))

Running this on Python 3.10 prints:

bar
1

And not

BAR
BAR

as the changelog states:

Changed Enum.format() (the default for format(), str.format() and f-strings) of enums with mixed-in types (e.g. int, str) to also include the class name in the output, not just the member’s key. This matches the existing behavior of enum.Enum.str(), returning e.g. 'AnEnum.MEMBER' for an enum AnEnum(str, Enum) instead of just 'MEMBER'.

I noticed this because we were using the str mixin with all Enum classes as a hack to get to the value without needing to write Foo.BAR.value 🫣 The new behavior in Python 3.11 broke our code and the current phrasing in the changelog makes it feel this was just a minor bugfix. Should this change be a bit more prominent since it can be a breaking change?

By the way, thank you for adding StrEnum, it's exactly what we needed!

PS: Not sure if this needs a GitHub issue number, it's not exactly a typo, but it's still a minor change. ~~I'm happy to open an issue if needed.~~ Issue linked below. Also let me know if I need to open the PR against any other branches as well. 🙇

Issue: Enum with str or int Mixin Breaking Change in Python 3.11 #100458

ghost

All commit authors signed the Contributor License Agreement.

Co-authored-by: JosephSBoyle <48555120+JosephSBoyle@users.noreply.github.com>

anze3db

@JosephSBoyle thank you! I've added your changes. Let me know if there is anything else needed from my side. Should I also open a PR against the 3.11 branch?

ethanfurman

@anze3db No need, once this is committed a backport PR will be automatically created.

anze3db

@JosephSBoyle there was more than a month of inactivity on this PR 😞 Anything I can do to help this getting merged?

JosephSBoyle

Hi @anze3db, I'm not a maintainer so perhaps this is a better question for @AlexWaygood. If the assigned reviewer is busy perhaps another reviewer can be assigned.

Bktero

Will this PR finds its way to the next version of Python?

Further question: is this change documented here https://docs.python.org/3/library/enum.html ? I can't spot it...

ethanfurman

My apologies -- I didn't get the [Submit Review] button pressed.

bedevere-bot

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

anze3db

I have made the requested changes; please review again.

bedevere-bot

Thanks for making the requested changes!

@ethanfurman: please review the changes made to this pull request.

anze3db

@ethanfurman just a friendly reminder to re-review this if you have the time, thanks!

ethanfurman

Did some rewriting in an attempt to make it clearer.

Thoughts on the new changes?

miss-islington

Thanks @anze3db for the PR, and @ethanfurman for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

…n the whatsnew/3.11.rst (pythonGH-100387) (cherry picked from commit e665563) Co-authored-by: Anže Pečar <anze@pecar.me> Co-authored-by: JosephSBoyle <48555120+JosephSBoyle@users.noreply.github.com> Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

bedevere-bot

GH-104060 is a backport of this pull request to the 3.11 branch.

…in the whatsnew/3.11.rst (GH-100387) (GH-104060) Co-authored-by: Anže Pečar <anze@pecar.me> Co-authored-by: JosephSBoyle <48555120+JosephSBoyle@users.noreply.github.com> Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

* main: (463 commits) pythongh-104057: Fix direct invocation of test_super (python#104064) pythongh-87092: Expose assembler to unit tests (python#103988) pythongh-97696: asyncio eager tasks factory (python#102853) pythongh-84436: Immortalize in _PyStructSequence_InitBuiltinWithFlags() (pythongh-104054) pythongh-104057: Fix direct invocation of test_module (pythonGH-104059) pythongh-100458: Clarify Enum.__format__() change of mixed-in types in the whatsnew/3.11.rst (pythonGH-100387) pythongh-104018: disallow "z" format specifier in %-format of byte strings (pythonGH-104033) pythongh-104016: Fixed off by 1 error in f string tokenizer (python#104047) pythonGH-103629: Update Unpack's repr in compliance with PEP 692 (python#104048) pythongh-102799: replace sys.exc_info by sys.exception in inspect and traceback modules (python#104032) Fix typo in "expected" word in few source files (python#104034) pythongh-103824: fix use-after-free error in Parser/tokenizer.c (python#103993) pythongh-104035: Do not ignore user-defined `__{get,set}state__` in slotted frozen dataclasses (python#104041) pythongh-104028: Reduce object creation while calling callback function from gc (pythongh-104030) pythongh-104036: Fix direct invocation of test_typing (python#104037) pythongh-102213: Optimize the performance of `__getattr__` (pythonGH-103761) pythongh-103895: Improve how invalid `Exception.__notes__` are displayed (python#103897) Adjust expression from `==` to `!=` in alignment with the meaning of the paragraph. (pythonGH-104021) pythongh-88496: Fix IDLE test hang on macOS (python#104025) Improve int test coverage (python#104024) ...

Clarify Enum.__format__() change of mixed-in types

e51f55c

bedevere-bot added awaiting review docs Documentation in the Doc dir skip news labels Dec 21, 2022

kumaraditya303 assigned ethanfurman Dec 23, 2022

anze3db mentioned this pull request Dec 23, 2022

Enum with str or int Mixin Breaking Change in Python 3.11 #100458

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anze3db changed the title ~~Clarify Enum.__format__() change of mixed-in types in the whatsnew/3.11.rst~~ Dec 23, 2022

JosephSBoyle reviewed Dec 27, 2022

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anze3db and others added 4 commits December 27, 2022 14:47

Point users to StrEnum or IntEnum for old formatting behavior …

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Co-authored-by: JosephSBoyle <48555120+JosephSBoyle@users.noreply.github.com>

Merge branch 'main' into main

3311e3d

Split into multiple ines

0d265a0

Fix small typo

5f30054

anze3db requested a review from JosephSBoyle December 27, 2022 15:08

ethanfurman added 3.11 only security fixes 3.12 only security fixes labels Dec 27, 2022

AlexWaygood added the needs backport to 3.11 only security fixes label Dec 27, 2022

JosephSBoyle approved these changes Dec 27, 2022

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bedevere-bot added awaiting core review and removed awaiting review labels Dec 27, 2022

AlexWaygood self-requested a review January 31, 2023 09:39

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Address PR feedback

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bedevere-bot added awaiting change review and removed awaiting changes labels Mar 22, 2023

bedevere-bot requested a review from ethanfurman March 22, 2023 19:07

update prose

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ethanfurman reviewed Apr 18, 2023

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ethanfurman merged commit e665563 into python:main May 1, 2023

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bedevere-bot removed the needs backport to 3.11 label May 1, 2023

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