Ken Jin <kenjin4...@gmail.com> added the comment:
I don't understand your example, T | None doesn't return a types.Union object, it returns typing.Union/typing.Optional. (I'm assuming this T is the TypeVar in typing). Which *is* subscriptable. >>> (T | None)[int].__origin__ typing.Union If you meant to say: why is typing.Union[] allowed, but not types.UnionType[]? That is intentional. types.UnionType is only meant for builtin types. Once you union with *any* type from typing, it will convert to a typing.Union. >>> type(int | str) <class 'types.UnionType'> >>> int | str | T typing.Union[int, str, ~T] If you intend to reconstruct a types.Union from another types.Union, you can do: args = get_args(int | str) import operator, functools functools.reduce(operator.or_, args) And guard this code with an isinstance(tp, types.UnionType) check. ---------- nosy: +gvanrossum, kj, serhiy.storchaka status: open -> pending _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue45418> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
