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Mixin repr overrides Enum repr in some cases #83768

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rmccampbell7 mannequin opened this issue Feb 8, 2020 · 6 comments
Closed

Mixin repr overrides Enum repr in some cases #83768

rmccampbell7 mannequin opened this issue Feb 8, 2020 · 6 comments
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@ethanfurman
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3.8 only security fixes 3.9 only security fixes 3.10 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@rmccampbell7
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rmccampbell7 mannequin commented Feb 8, 2020

BPO 39587
Nosy @warsaw, @ethanfurman, @miss-islington, @tirkarthi
PRs
  • bpo-39587: Enum - use correct mixed-in data type #22263
  • [3.8] bpo-39587: Enum - use correct mixed-in data type (GH-22263) #22265
  • [3.9] bpo-39587: Enum - use correct mixed-in data type (GH-22263) #22266
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    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 = 'https://github.com/ethanfurman'
closed_at = <Date 2020-09-16.00:01:58.020>
created_at = <Date 2020-02-08.21:01:31.642>
labels = ['3.8', 'type-bug', 'library', '3.9', '3.10']
title = 'Mixin repr overrides Enum repr in some cases'
updated_at = <Date 2020-09-16.00:01:58.020>
user = 'https://bugs.python.org/rmccampbell7'

    bugs.python.org fields:

    activity = <Date 2020-09-16.00:01:58.020>
actor = 'ethan.furman'
assignee = 'ethan.furman'
closed = True
closed_date = <Date 2020-09-16.00:01:58.020>
closer = 'ethan.furman'
components = ['Library (Lib)']
creation = <Date 2020-02-08.21:01:31.642>
creator = 'rmccampbell7'
dependencies = []
files = []
hgrepos = []
issue_num = 39587
keywords = ['patch']
message_count = 6.0
messages = ['361635', '361667', '376959', '376962', '376963', '376966']
nosy_count = 6.0
nosy_names = ['barry', 'eli.bendersky', 'ethan.furman', 'rmccampbell7', 'miss-islington', 'xtreak']
pr_nums = ['22263', '22265', '22266']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue39587'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']
    @rmccampbell7
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    rmccampbell7 mannequin commented Feb 8, 2020

    In Python 3.6 the following works:

    class HexInt(int):
    def __repr__(self):
        return hex(self)

class MyEnum(HexInt, enum.Enum):
    A = 1
    B = 2
    C = 3
    >>> MyEnum.A
<MyEnum.A: 0x1>

However in Python 3.7/8 it instead prints
>>> MyEnum.A
0x1

    It uses HexInt's repr instead of Enum's. Looking at the enum.py module it seems that this occurs for mixin classes that don't define __new__ due to a change in the _get_mixins_ method. If I define a __new__ method on the HexInt class then the expected behavior occurs.

    @rmccampbell7 rmccampbell7 mannequin added 3.7 (EOL) end of life 3.8 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Feb 8, 2020
    @tirkarthi
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    Bisecting points to bpo-29577 that introduced this change.

    @ethanfurman ethanfurman added 3.9 only security fixes 3.10 only security fixes and removed 3.7 (EOL) end of life labels Sep 15, 2020
    @ethanfurman
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    Yes, the change only considered types with their own copy of __new__ to be actual data types, so in 3.6 HexInt was the recognized data type, but in 3.7+ it was int -- which also meant that HexEnum was considered a simple mix-in and its __repr__ was used instead of Enum.__repr__.

    @ethanfurman
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    New changeset bff01f3 by Ethan Furman in branch 'master':
    bpo-39587: Enum - use correct mixed-in data type (GH-22263)
    bff01f3

    @miss-islington
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    New changeset 8f8ebcc by Miss Islington (bot) in branch '3.8':
    bpo-39587: Enum - use correct mixed-in data type (GH-22263)
    8f8ebcc

    @ethanfurman
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    New changeset 95b81e2 by Miss Islington (bot) in branch '3.9':
    bpo-39587: Enum - use correct mixed-in data type (GH-22263) (GH-22266)
    95b81e2

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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    @ethanfurman ethanfurman

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