Python Composite Desing Pattern - RecursionError: maximum recursion depth exceeded

Question

所以我浏览了一些设计模式书籍，然后我决定在 python 中制作自己的书籍（这本书是为 Java 编写的），我偶然发现了这个我不能的问题解决，我在这里错过了什么？

那么为什么我会出现递归错误？

class Component:

    _components = []

    def __init__(self, value):
        self.value = value

    def add(self, *components):
        self._components.extend(components)

    def remove(self, *components):
        self._components = list(set(self._components).difference(set(components)))

    def get_components(self):
        return self._components

    def __repr__(self):
        return "Component value: {}".format(self.value)


class ComputerComponent(Component):

    def turn_on(self):
        self.on = True
        for component in self.get_components( ):
            component.turn_on( )
        print("{} turned on".format(self.value))



class Computer(ComputerComponent):
    pass

class LCDScreen(ComputerComponent):
    pass

class Mouse(ComputerComponent):
    pass

class Keyboard(ComputerComponent):
    pass

computer = Computer("computer")
lcd_screen = LCDScreen("lcd_screen")
mouse = Mouse("mouse")
keyboard = Keyboard("keyboard")

computer.add(lcd_screen,mouse,keyboard)

computer.turn_on( )

Answer 1

_components 应该是实例变量，而不是 class 变量。实际上，将组件添加到计算机会将它们添加到所有其他组件。也就是说，每个组件都是其他所有组件的组件，这会导致无限循环。

class Component:

    def __init__(self, value):
        self.value = value
        self._components = []

    def add(self, *components):
        self._components.extend(components)

    def remove(self, *components):
        self._components = list(set(self._components).difference(set(components)))

    def get_components(self):
        return self._components

    def __repr__(self):
        return "Component value: {}".format(self.value)

Python Composite Desing Pattern - RecursionError: maximum recursion depth exceeded

Python Composite Desing Pattern - RecursionError: maximum recursion depth exceeded

python

recursion

composite