proxy-object.py

from typing import Protocol, TypeVar, Generic, Any


T = TypeVar('T')


class Proxy(Generic[T]):
    def __init__(self, proxied: T) -> None:
        self._proxied = proxied

    def __getattr__(self, item: str) -> Any:
        return getattr(self._proxied, item)


class Client(Protocol):
    def do_something(self) -> None:
        ...

    def do_another_thing(self) -> None:
        ...


class InnerClient:
    def do_something(self) -> None:
        print("InnerClient.do_something")

    def do_another_thing(self) -> None:
        print("InnerClient.do_another_thing")


class OuterClient1(Proxy[Client]):
    def do_something(self) -> None:
        print("OuterClient1.do_something")
        self._proxied.do_something()


class OuterClient2(Proxy[Client]):
    def __init__(self, client: Client, num: int):
        super().__init__(client)
        self._num = num

    def do_another_thing(self) -> None:
        print(f"OuterClient2.do_another_thing {self._num}")
        self._proxied.do_another_thing()


def main() -> None:
    inner_client: Client = InnerClient()
    outer_client_1: Client = OuterClient1(inner_client)
    outer_client_2: Client = OuterClient2(outer_client_1, 42)

    outer_client_2.do_something()
    outer_client_2.do_another_thing()


if __name__ == "__main__":
    main()