Python中如何实现命令模式？

from abc import ABC, abstractmethod

# 命令接口
class Command(ABC):
    @abstractmethod
    def execute(self):
        pass

# 具体命令类
class LightOnCommand(Command):
    def __init__(self, light):
        self.light = light

    def execute(self):
        self.light.turn_on()

class LightOffCommand(Command):
    def __init__(self, light):
        self.light = light

    def execute(self):
        self.light.turn_on()

# 接收者
class Light:
    def turn_on(self):
        print("Light is on")

    def turn_off(self):
        print("Light is off")

# 调用者
class RemoteControl:
    def __init__(self):
        self.command = None

    def set_command(self, command):
        self.command = command

    def press_button(self):
        if self.command:
            self.command.execute()

# 使用示例
light = Light()
light_on = LightOnCommand(light)
light_off = LightOffCommand(light)

remote = RemoteControl()
remote.set_command(light_on)
remote.press_button()  # 输出: Light is on

remote.set_command(light_off)
remote.press_button()  # 输出: Light is off

class DrawCommand(Command):
    def __init__(self, shape, x, y):
        self.shape = shape
        self.x = x
        self.y = y

    def execute(self):
        self.shape.draw(self.x, self.y)

    def undo(self):
        self.shape.erase(self.x, self.y)

class Shape(ABC):
    @abstractmethod
    def draw(self, x, y):
        pass

    @abstractmethod
    def erase(self, x, y):
        pass

class Circle(Shape):
    def draw(self, x, y):
        print(f"Drawing a circle at ({x}, {y})")

    def erase(self, x, y):
        print(f"Erasing a circle at ({x}, {y})")

class DrawingApp:
    def __init__(self):
        self.commands = []
        self.undo_stack = []

    def execute(self, command):
        command.execute()
        self.commands.append(command)
        self.undo_stack = []

    def undo(self):
        if self.commands:
            command = self.commands.pop()
            command.undo()
            self.undo_stack.append(command)

    def redo(self):
        if self.undo_stack:
            command = self.undo_stack.pop()
            command.execute()
            self.commands.append(command)

# 使用示例
app = DrawingApp()
circle = Circle()

app.execute(DrawCommand(circle, 10, 20))  # 输出: Drawing a circle at (10, 20)
app.undo()  # 输出: Erasing a circle at (10, 20)
app.redo()  # 输出: Drawing a circle at (10, 20)