Threaddef good_singleton(class_: Type) -> Callable[..., Any]:

def good_singleton(class_: Type) -> Callable[..., Any]: """ Singleton decorator. If instance of class already exists, raises ValueError. It blocks creating new instances of classes that should instantiate only once. """ instances: Dict[Type, Any] = {} def getinstance(*args, **kwargs) -> Any: if class_ not in instances: instances[class_] = class_(*args, **kwargs) return instances[class_] raise ValueError(f"Instance of {class_} already exists") return getinstance Я изобрел хороший синглтон!