A delegator

delegator.py

from typing import Any
import unittest

class Delegator:
    def __init__(self, instance, method_name):
        self.instance = instance
        self.method_name = method_name

    def __getattr__(self, name):
        if name == self.method_name:
            return getattr(self.instance, name)
        raise AttributeError(f"'{self.__class__.__name__}' object has no attribute '{name}'")

    def __call__(self, *args: Any, **kwds: Any) -> Any:
        return getattr(self.instance, self.method_name)(*args, **kwds)

    def __get__(self, instance, owner):
        if instance is None:
            return self
        return getattr(self.instance, self.method_name)

class Bar:
    buzz = "buzz"
    def hello(self):
        return "Hello from Bar"

class Foo:
    bar = Bar()
    hello = Delegator(bar, 'hello')
    buzz = Delegator(bar, 'buzz')

class TestMe(unittest.TestCase):
    def test_delegator(self):
        foo = Foo()
        self.assertEqual(foo.bar.hello(), foo.hello())
        self.assertEqual(foo.bar.buzz, foo.buzz)

delegator2.py

class Delegator:
    def __getattr__(self, name):
        if hasattr(self, 'delegate'):
            target_attr, methods = self.delegate
            if name in methods:
                target = getattr(self, target_attr)
                return getattr(target, name)
        raise AttributeError(f"'{self.__class__.__name__}' object has no attribute '{name}'")

class Buzz(Delegator):
    delegate = ['model', ['hello', 'bye']]

    def __init__(self):
        self.model = Bar()

b = Buzz()

print(b.hello())
print(b.bye("Joe"))
b.not_implemented()