Python中的抽象工厂模式

Question

我今天一直在阅读有关抽象工厂模式的文章，并试图做以下实现。

我在互联网上看到了很多实现，他们使用switch语句，但我必须说，我不太喜欢它，因为你制造的工厂越多，在我看来，如果需要的话，增加新产品是非常困难的。

总之，我希望你能看一看，告诉我你的意见。提前感谢您花时间复习。

工厂

from abc import ABC, abstractmethod


class PlayerFactory(ABC):
    """
    This class is meant to be an interface
    """
    @abstractmethod
    def create_goalkeeper(self):
        pass

    @abstractmethod
    def create_defender(self):
        pass


class FootballPlayerFactory(PlayerFactory):
    def create_goalkeeper(self):
        return FootballGoalkeeper()

    def create_defender(self):
        return FootballDefender()


class HockeyPlayerFactory(PlayerFactory):
    def create_goalkeeper(self):
        return HockeyGoalkeeper()

    def create_defender(self):
        return HockeyDefender()

足球运动员

class FootballPlayer:
    def __init__(self, uses_hands):
        self.uses_hands = uses_hands

    def play(self):
        print("I'm playing football!")


class FootballGoalkeeper(FootballPlayer):
    def __init__(self):
        super(FootballGoalkeeper, self).__init__(uses_hands=True)


class FootballDefender(FootballPlayer):
    def __init__(self):
        super(FootballDefender, self).__init__(uses_hands=False)

曲棍球运动员(我的创造力在这里停止了，所以我不包括守门员和后卫之间的任何区别)。

class HockeyPlayer:
    def play(self):
        print("I'm playing hockey!")


class HockeyGoalkeeper(HockeyPlayer):
    pass


class HockeyDefender(HockeyPlayer):
    pass

Answer 1

按照您当前的代码，您不需要派生工厂类。它们之间没有什么不同，所以它们都可以由一个具体的基类来处理。

class PlayerFactory:

    def __init__(self, goal_keeper_class, defender_class):
        self._goal_keeper_class = goal_keeper_class
        self._defender_class = defender_class

    def create_goalkeeper(self):
        return self._goal_keeper_class()

    def create_defender(self):
        return self._defender_class()

player_factory = {
    "Football": PlayerFactory(FootballGoalkeeper, FootballDefender),
    "Hockey": PlayerFactory(HockeyGoalkeeper, HockeyDefender),
}

示例用法：

>>> player = player_factory["Hockey"].create_defender()
>>> type(player)
<class '__main__.HockeyDefender'>
>>> player.play()
I'm playing hockey!
>>>

如果工厂的某些方面实际上做了一些不同的事情，因此需要分离派生类，那么您就需要将其包含在问题中。