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Make the 2 last parameters for typing.Generator optional #4221
Description
If I use:
Generator[int]
mypy complains:
error: "Generator" expects 3 type arguments, but 1 given
I can silence mypy by doing:
Generator[int, None, None]
But given that the majority of generators just yield, rarely return or send, I think it would make sense to allow the last 2 parameters to have a default value of None.
Activity
emmatyping commentedon Nov 8, 2017
This issue is probably better suited to be discussed in the typing repo https://github.com/python/typing
JukkaL commentedon Nov 8, 2017
Is there a reason you can't use
Iterator[int]as the return type?zeth commentedon Dec 1, 2021
Because the type is a Generator. Are we annotating the types or not?
hauntsaninja commentedon Dec 1, 2021
We are annotating the types, all three of them, yield send and return ;-) For everything else, there's Iterator.
While I don't think this is a compelling case since there's a solution that works perfectly well, I'm sympathetic to the idea of defaults for generic types in general. The forum to take that issue up is the typing-sig mailing list or https://github.com/python/typing, not here