Manage inheritance correctly

[tmke8]

Only Generic and other TypeEnums should be allowed. See how it's done with TypedDict: https://github.com/python/cpython/blob/32220543e2db36c6146ff2704ed1714a6adecc1b/Lib/typing.py#L2931

[tmke8]

Actually, maybe inheriting from other TypeEnums also shouldn't be allowed because this will mess up the exhaustiveness check.

[tmke8]

It should work like this: You can do inheritance but the inner types of a subclass are not members of the base class. So, BgColor.transparent is not a subclass of Color even if BgColor inherits from Color.

[tmke8]

There is another point: T.A should actually have all the attributes that T has, otherwise it's really not appropriate to call it a subclass. So, you can access A also through T.A.A and so on.

[tmke8]

Note also, that if we have

class Color(TypeEnum):
    rgb = (int, int, int)
class BgColor(Color):
    hsv = (int, int, int)

then BgColor should not be a subclass of Color:

assert not issubclass(BgColor, Color)

which is admittedly a bit weird... but otherwise BgColor.hsv would be a subtype of Color.