from dataclasses import dataclass
from types import LambdaType, FunctionType
from typing import Mapping, Type, TypeVar

T = TypeVar("T")

class ServiceLookupException(Exception):
    pass 

@dataclass
class ServiceContainer:
    _singletons: Mapping[str, T]
    _factories: Mapping[str, T]
    
    def register(self, name: str, instance: T) -> None:
        if type(instance) is LambdaType or type(instance) is FunctionType:
            self._factories[name] = instance
        else:
            self._singletons[name] = instance
            
    def retrieve(self, name: str, _: Type[T]) -> T:
        if name in self._singletons:
            return self._singletons[name]
        elif name in self._factories:
            return self._factories[name]()
        
        raise ServiceLookupException(f"Could not locate service with name {name}")
        
        
@dataclass
class Foo:
    bar: str
    
    def __post_init__(self):
        print(f"Initialized with {self.bar}")
    
    
container = ServiceContainer({}, {})
container.register("foo_lam", lambda : Foo("bar"))
foo_single = Foo("baz")
container.register("foo_single", foo_single)

mc1 = container.retrieve("foo_lam", Type[Foo])
mc2 = container.retrieve("foo_lam", Type[Foo])
mc3 = container.retrieve("foo_single", Type[Foo])
mc4 = container.retrieve("foo_single", Type[Foo])

print(mc1.bar)
print(mc2.bar)
print(mc3.bar)
print(mc4.bar)