Defining my own None-like Python constant

Question

I have a situation in which I\'m asked to read collections of database update instructions from a variety of sources. All sources will contain a primary key value so that t

Answer 1

If you want type-checking, this idiom is now blessed by PEP 484 and supported by mypy:

from enum import Enum

class NotInFileType(Enum):
    _token = 0

NotInFile = NotInFileType._token

If you are using mypy 0.740 or earlier, you need to workaround this bug in mypy by using typing.Final:

from typing import Final

NotInFile: Final = NotInFileType._token

If you are using Python 3.7 or earlier, you can use typing_extensions.Final from pip package typing_extensions instead of typing.Final