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Using NamedTuple with custom Enum #114149
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This issue is related to #114071 and @ethanfurman suggested creating an isolated issue:
The handling of NamedTuple with a custom Enum is unexpected. Here are two examples that seek to achieve the same thing, but one will fail when using NamedTuple.
Using dataclasses (works):
Details
from dataclasses import dataclass
from enum import Enum
@dataclass
class CodeLabel:
code: int
label: str
class LabelledEnumMixin:
labels = {}
def __new__(cls, codelabel: CodeLabel):
member = object.__new__(cls)
member._value_ = codelabel.code
member.label = codelabel.label
cls.labels[codelabel.code] = codelabel.label
return member
@classmethod
def list_labels(cls):
return list(l for c, l in cls.labels.items())
class Test(LabelledEnumMixin, Enum):
A = CodeLabel(1, "Label A")
B = CodeLabel(2, "Custom B")
C = CodeLabel(3, "Custom label for value C + another string")
Test.list_labels()Using NamedTuple (fails):
Details
from typing import NamedTuple
from enum import Enum
class CodeLabel(NamedTuple):
code: int
label: str
class LabelledEnumMixin:
labels = {}
def __new__(cls, codelabel: CodeLabel):
member = object.__new__(cls)
member._value_ = codelabel.code
member.label = codelabel.label
cls.labels[codelabel.code] = codelabel.label
return member
@classmethod
def list_labels(cls):
return list(l for c, l in cls.labels.items())
class Test(LabelledEnumMixin, Enum):
A = CodeLabel(1, "Label A")
B = CodeLabel(2, "Custom B")
C = CodeLabel(3, "Custom label for value C + another string")
Test.list_labels()Linked PRs
- gh-114149: fix tuple subclass handling when using custom __new__Â #114160
- [3.12] gh-114149: [Enum] fix tuple subclass handling when using custom __new__ (GH-114160)Â #114196
- [3.11] gh-114149: [Enum] fix tuple subclass handling when using custom __new__ (GH-114160)Â #114197
- gh-114149: [Enum] revert #114160 and add more tuple-subclass tests #114215
- [3.12] gh-114149: [Enum] revert GH-114196 and add more tuple-subclass tests (GH-114215)Â #114218
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gh-114149: [Enum] fix tuple subclass handling when using custom __newâĶ
pythongh-114149: [Enum] fix tuple subclass handling when using customâĶ
3 remaining items
SultanOrazbayev commentedon Jan 17, 2024
It does seem like a correct behavior for a tuple, but it is a bit unexpected because tuples are treaded in a special way (re: the original issue). So perhaps this is resolvable by documenting the special treatment of tuples in
__new__?ethanfurman commentedon Jan 18, 2024
That is my thought.
gh-114149: [Enum] revert #114160 and add more tuple-subclass tests (GâĶ
pythongh-114149: [Enum] revert pythonGH-114160 and add more tuple-subâĶ
[3.12] gh-114149: [Enum] revert GH-114196 and add more tuple-subclassâĶ
pythongh-114149: [Enum] fix tuple subclass handling when using customâĶ
pythongh-114149: [Enum] revert python#114160 and add more tuple-subclâĶ
pythongh-114149: [Enum] fix tuple subclass handling when using customâĶ
pythongh-114149: [Enum] revert python#114160 and add more tuple-subclâĶ
pythongh-114149: [Enum] fix tuple subclass handling when using customâĶ
pythongh-114149: [Enum] revert python#114160 and add more tuple-subclâĶ