Python typing: how to name a new type?

Question

I wanted to give a name to a dict type, something like:

MyDictType = Dict[int, SomeClass]

and so I found about NewType, but it seems to only accepts runtime types:
the code MyDictType = NewType('MyDictType', Dict[int, SomeClass]
creates the warning Expected type 'Type[_T]', got '_VT' instead

So what is the correct way to do this?

*I'm using Python 3.7 . Please let me know if there's a better solution in newer versions.

Answer 1

You can do

from typing import NewType

MyDictType = NewType("MyDictType", Dict[int, SomeClass])

NewType was added in 3.5.2, but behaviour changed in 3.10. Here're the docs for 3.10: https://docs.python.org/3/library/typing.html#typing.NewType