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

anze3db · 2022-12-21T02:50:42Z

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

cpython-cla-bot · 2022-12-21T02:51:12Z

All commit authors signed the Contributor License Agreement.

Doc/whatsnew/3.11.rst

Co-authored-by: JosephSBoyle <[email protected]>

anze3db · 2022-12-27T15:08:24Z

@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 · 2022-12-27T17:44:48Z

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

anze3db · 2023-01-31T08:14:13Z

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

JosephSBoyle · 2023-01-31T09:27:10Z

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 · 2023-03-22T14:58:54Z

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.

ethanfurman · 2023-02-01T21:11:05Z

Doc/whatsnew/3.11.rst

@@ -676,10 +676,12 @@ enum
 * Changed :meth:`Enum.__format__() <enum.Enum.__format__>`
  (the default for :func:`format`, :meth:`str.format` and :term:`f-string`\s)
  of enums with mixed-in types (e.g. :class:`int`, :class:`str`)
-  to also include the class name in the output, not just the member's key.
+  to include the class name and member key in the output, not the member's value.


Suggested change

to include the class name and member key in the output, not the member's value.

to show the class name and member name in the output, instead of the member's value.

ethanfurman · 2023-02-01T21:14:33Z

Doc/whatsnew/3.11.rst

@@ -676,10 +676,12 @@ enum
 * Changed :meth:`Enum.__format__() <enum.Enum.__format__>`
  (the default for :func:`format`, :meth:`str.format` and :term:`f-string`\s)
  of enums with mixed-in types (e.g. :class:`int`, :class:`str`)
-  to also include the class name in the output, not just the member's key.
+  to include the class name and member key in the output, not the member's value.
  This matches the existing behavior of :meth:`enum.Enum.__str__`,
  returning e.g. ``'AnEnum.MEMBER'`` for an enum ``AnEnum(str, Enum)``


Suggested change

returning e.g. ``'AnEnum.MEMBER'`` for an enum ``AnEnum(str, Enum)``

returning e.g. ``'AnEnum.MEMBER'`` for an enum ``AnEnum(str, Enum)``.

ethanfurman · 2023-02-01T21:14:50Z

Doc/whatsnew/3.11.rst

  This matches the existing behavior of :meth:`enum.Enum.__str__`,
  returning e.g. ``'AnEnum.MEMBER'`` for an enum ``AnEnum(str, Enum)``
-  instead of just ``'MEMBER'``.
+  instead of the member's value. Those wishing to keep the old formatting behavior


Suggested change

instead of the member's value. Those wishing to keep the old formatting behavior

Those wishing to keep the old formatting behavior

bedevere-bot · 2023-03-22T16:53:53Z

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 · 2023-03-22T19:07:00Z

I have made the requested changes; please review again.

bedevere-bot · 2023-03-22T19:07:05Z

Thanks for making the requested changes!

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

anze3db · 2023-04-13T13:42:24Z

@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 · 2023-05-01T19:49:58Z

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 <[email protected]> Co-authored-by: JosephSBoyle <[email protected]> Co-authored-by: Ethan Furman <[email protected]>

bedevere-bot · 2023-05-01T19:50:08Z

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 <[email protected]> Co-authored-by: JosephSBoyle <[email protected]> Co-authored-by: Ethan Furman <[email protected]>

* 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

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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~~ gh-100458: 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

4ccc0fe

Co-authored-by: JosephSBoyle <[email protected]>

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 bugs and 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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update prose

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

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

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	to include the class name and member key in the output, not the member's value.
	to show the class name and member name in the output, instead of the member's value.

	returning e.g. ``'AnEnum.MEMBER'`` for an enum ``AnEnum(str, Enum)``
	returning e.g. ``'AnEnum.MEMBER'`` for an enum ``AnEnum(str, Enum)``.

	instead of the member's value. Those wishing to keep the old formatting behavior
	Those wishing to keep the old formatting behavior

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

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

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

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

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