[Typing-sig] Re: Literal for constants

24 Nov 2020

      I recently ran across some Django code that has an interesting solution for typing a sentinel object: It uses a *type* object as a sentinel rather than just an `object()`:

    # django/db/models/fields/__init__.py

    class NOT_PROVIDED:
        pass

    class Field(RegisterLookupMixin):
        def __init__(self, ..., default=NOT_PROVIDED, ...):
            ...

Presumably the type of the `default` parameter could then be written as:

    Union[Type[NOT_PROVIDED], Any]

Not exactly direct, but may work.

--
David Foster | Seattle, WA, USA
Contributor to TypedDict support for mypy