结构型模式 - 装饰器模式

允许向一个现有的对象添加新的功能，而且不改变类的结构。

Demo

"""
装饰器模式
"""
class Shape:
    def draw(self):
        raise NotImplementedError
class Circle(Shape):
    def draw(self):
        print("this is circle")
class ShapeDecorator:
    def __init__(self, shape: Shape):
        self.shape = shape
    def draw(self):
        self.shape.draw()
class RedShapeDecorator(ShapeDecorator):
    def draw(self):
        super(RedShapeDecorator, self).draw()
        print('color is red')
if __name__ == '__main__':
    c = Circle()
    c.draw()
    print("=" * 10)
    red_c = RedShapeDecorator(Circle())
    red_c.draw()