Description
In this StackOverflow answer, Ethan Furman, the author of the enum module, demonstrated how a tuple value is special-cased so that it can be unpacked as arguments to the constructor of the mixin type, making it possible to extremely elegantly implement a member type with additional information such as a label for each member as requested by the SO question:
from enum import Enum
class LabelledEnumMixin:
labels = {}
def __new__(cls, value, label):
member = object.__new__(cls)
member._value_ = value
member.label = label
cls.labels[value] = label
return member
@classmethod
def list_labels(cls):
return list(l for c, l in cls.labels.items())
class Test(LabelledEnumMixin, Enum):
A = 1, "Label A"
B = 2, "Custom B"
C = 3, "Custom label for value C + another string"
print(list(Test))
print(Test.list_labels())This outputs:
[<Test.A: 1>, <Test.B: 2>, <Test.C: 3>]
['Label A', 'Custom B', 'Custom label for value C + another string']
Such a neat behavior of a tuple value is currently undocumented in the Supported __dunder__ names section of the enum's docs, however, making it more of an implementation detail rather than a publicly usable feature.
Please help document this feature properly so we can all benefit from the new possibilities this feature enables without fearing that we are using an undocumented implementation detail. Thanks.