Disallow instantiating a Protocol class · Issue #12261 · python/mypy (original) (raw)

The following gives an error in Pyright and I think it should give an error in MyPy as well:

from typing import Protocol

class Foo(Protocol): ...

Foo()

https://mypy-play.net/?mypy=latest&python=3.10&gist=f4ca0ee490d9e8b3a117ee785b7bdaf6

I think that even if the protocol class implements an __init__ method, this should still be disallowed:

from typing import Protocol

class Foo(Protocol): def init(self) -> None: pass

Foo() # disallowed

class ConcreteFoo(Foo): ...

ConcreteFoo() # allowed