Implement TypeVar bounds with an intersection bound

[graingert]

For type variables that extend multiple interfaces

<T extends I1 & I2>

[gvanrossum]

Can you describe your use case for this feature, with some examples?

It sounds related to the Intersection proposed in the typing repo.

In general a new feature like this should probably be discussed in the typing repo first, since it would require changes to the typing.py module (which is gated by stdlib releases).

[ilevkivskyi]

@gvanrossum Assuming the original syntax is taken from Java, this is what I proposed in the issue you mentioned, T = TypeVar('T', bound=Intersection[t1, t2]). As I mentioned in that issue, the most obvious use case is when types t1, t2 are ABCs (similar to interfaces in Java).

[graingert]

ah yes, this is just python/typing#213 I was searching under TypeVar

[gvanrossum]

OK, closing in favor of #213.