from dataclasses import dataclass
from typing import Mapping, Type, TypeVar

T = TypeVar("T")

@dataclass
class ServiceContainer:
    _dependencies: Mapping[str, T] = {}

    def register(self, name: str, instance: T) -> None:
        self._dependencies[name] = instance

    def retrieve(self, name: str, _: Type[T]) -> T:
        return self._dependencies[name]



# in python 3.12 we can use retrieve[T] :)
# https://docs.python.org/3/reference/compound_stmts.html#type-params