Add missing _add_value_alias_ method for Python 3.13 enum

[tjdcs]

Fixes #14408

[srittau]

Thanks, remarks below. We should also add overridden variants of this method to StrEnum and IntEnum, similar to what we do for other attributes/methods where value is used.

Also, for future reference: Please don't use AI PR summaries. Those use a lot of words for something very simple, making it considerably harder to understand the issue and PR. In this case, a simple link back to the original issued would have sufficed.

[srittau]

These tests don't seem to test anything relevant – at least not as it relates to type annotations. We generally don't run our test cases, we just type check them, so any logic is meaningless. This is also seems to test something called a MultiValueEnum, which isn't a concept in Python's stdlib.

[srittau]

We nowadays require explanatory comments for all non-obvious Anys. In this case, maybe the following comment makes sense?

Suggested change

	def _add_value_alias_(self, value: Any) -> None: ...
	# value must have the same type as other enum members
	def _add_value_alias_(self, value: Any) -> None: ...

[tjdcs]

Hmm... Looking at your suggestion... is this true? I have implemented a str enum with int and other aliases...

from enum import Enum, StrEnum


class EOTFType(str, Enum):
    RESERVED = ("RESERVED", 0)
    SDR = ("SDR", 1)
    PQ = ("PQ", 2)
    HLG = ("HLG", 3)

    def __new__(cls, value: str, int_val: int):
        self = str.__new__(cls, value)
        self._value_ = value
        self._add_value_alias_(int_val)  # type: ignore Added in python 3.13
        return self

    def __init__(
        self,
        _: str,
        int_value: int,
    ):
        self.int_value = int_value

    def __str__(self) -> str:
        """
        Return a formatted string representation of the EOTF type.

        Returns
        -------
        str
            Format: "value=name" (e.g., "2=PQ")
        """
        return f'{self.value}="{self.value}"={self.int_value}'


class StrIntEnum(StrEnum):
    RED = "red"
    GREEN = "green"

def main():
    direct = EOTFType.PQ
    print(direct)

    parsed_int = EOTFType(2)
    print(parsed_int)

    parsed_str = EOTFType("PQ")
    print(parsed_str)

    print(f'parsed_str == "PQ": {parsed_str == "PQ"}')
    print(f'parsed_str == "PQ": {parsed_str == 2}')
    print(f'parsed_str.int_value == "PQ": {parsed_str.int_value == 2}')

    StrIntEnum.GREEN._add_value_alias_(4)
    print(StrIntEnum(4))


if __name__ == "__main__":
    main()

Is Any really the correct annotation here or is object better... as above?

As for the special enums (StrEnum, IntEnum)... It seems the alias can still be "any".

[donBarbos]

I would like to note that the _add_alias_ method was added in the same version, and it would be possible to add them together

[tjdcs]

Thank you for your comments. Give me a day or two to address them and correct this PR. I will add the requisite comments, remove the irrelevant tests, and check the additional special enum types.

Also, my apologies for the verbose PR summary. I was really just letting Claude run rampant and see what he did / what he came up with. I'll keep that in mind for the future.

[tjdcs]

Bringing this in-line with https://github.com/python/cpython/blob/3.13/Lib/enum.py#L1220-L1246

It seems like the docs page is missing the function signature. This is my first http://github.com/python contribution, so I may be a bit lost about what is correct or incorrect. Python Docs: EnumType._add_value_alias

I believe that IntEnum and StrEnum simply inherit the Enum behavior and do not impose additional type restrictions. Therefore, they do not need specific overrides for type checking.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[srittau]

Thanks!