Mastering Object-Oriented Python - Second Edition

Using the __subclasshook__() method

We can define abstract base classes with complex rules for overrides to create concrete subclasses. This is done by implementing the __subclasshook__() method of the abstract base class, as shown in the following code:

class AbstractBettingStrategy2(ABC):    @abstractmethod    def bet(self, hand: Hand) -> int:        return 1    @abstractmethod    def record_win(self, hand: Hand) -> None:        pass    @abstractmethod    def record_loss(self, hand: Hand) -> None:        pass    @classmethod    def __subclasshook__(cls, subclass: type) -> bool:        """Validate the class definition is complete."""        if cls is AbstractBettingStrategy2:            has_bet = any(hasattr(B, "bet") for B in subclass.__mro__)            has_record_win =  any(hasattr(B, "record_win") for B in subclass. ...