class ellipsis is public but shouldn't

[davidhalter]

Ellipsis is defined like this:

# Actually the type of Ellipsis is <type 'ellipsis'>, but since it's
# not exposed anywhere under that name, we make it private here.    
class ellipsis: ...
Ellipsis: ellipsis

However I do not see how this ellipsis does not leak. Wouldn't it be better to rename ellipsis to _ellipsis or import it from somewhere and not export it again?

[JelleZijlstra]

You're probably right, but I think mypy depends internally on the object being available under this name, so it might be fairly complicated to fix. (The same goes for builtins.function and builtins.module, which don't exist at runtime either.)

[davidhalter]

That's why I didn't patch it. #2999 is also from me.

My opinion is this: We should get closer to what Python actually does. Mypy is not the only typeshed user and is probably also not the biggest one in terms of user numbers.

[srittau]

I agree that we should work towards a fix, but currently mypy and typeshed are closely tied together and we can't make changes that will break mypy. This should probably be brought up in mypy's issue tracker of there isn't an issue already.

[davidhalter]

This should probably be brought up in mypy's issue tracker of there isn't an issue already.

Opened python/mypy#8240. Hopefully that helps.

typeshed are closely tied together and we can't make changes that will break mypy

It's a bit unfortunate that the CI's are circular (both depend on each other). However other than that, typeshed could depend on an older version of typeshed.

[gvanrossum]

In Python 3.10, there is now types.EllipsisType, the type of Ellispsis. We should add this to typeshed so we can change the type of Ellipsis to that (at least in 3.10+). Do we need to change mypy for this as well?

References: https://bugs.python.org/issue41810, python/cpython#22336, python/typing#684 (comment)

[AlexWaygood]

Closing as we now have #7580, and I don't think we need both issues to be open when they're about the same thing.