Typing a protocol with internal enum class

Typing
1

Hi all,
I’m struggling to define a protocol with an internal enum class that can be understood by mypy.

python: 3.10
mypy : 1.11.2

Here’s my attempt:

from __future__ import annotations
import enum
from typing import  Protocol


class PListItem(Protocol):

    class Role(enum.Enum):
        ...

    def get_data(self, role: Role) -> str:
        ...

The goal is to define a generic container of items. I use the protocol as a bound:

import enum
from collections.abc import Iterable
from typing import TypeVar, Generic

T = TypeVar('T', bound=PListItem)


class ListOfItems(Generic[T]):
    _collections: list[T]
    _roles: dict[int, T.Role]

    def __init__(self,collections: Iterable[T], type_data: type[T]):
        self._collections = list(collections)
        roles = type_data.Role
        self._roles = dict(enumerate(roles))


class Item:
    def __init__(self, name: str):
        self.name = name

    class Role(enum.Enum):
        NAME: str = "name"

    def get_data(self, role: Role) -> str:
        if role == self.Role.NAME:
            return self.name
        return ""


if __name__ == '__main__':
    d1 = Item("data1")
    d2 = Item("data2")
    lst = ListOfItems([d1, d2], type_data=Item)

mypy gives me to errors :

error: Name "T.Role" is not defined  [name-defined]
error: Value of type variable "T" of "ListModel" cannot be "Item"  [type-var]

I don’t understand why T.Role is not recognized, and I couldn’t find examples of protocols with attached classes.

Is there a better way to define the typing in this case?