2.2、组合模式

• 内容：将对象组合成树形结构以表示 “部分-整体” 的层次结构。组合模式使得用户对单个对象和组合对象的使用具有一致性。
• 角色：
  • 抽象组件（Component）
  • 叶子组件（Leaf）
  • 复合组件（Composite）
  • 客户端（Client）

from abc import abstractmethod, ABCMeta
class Graphic(metaclass=ABCMeta):
    @abstractmethod
    def draw(self):
        raise NotImplemented
    @abstractmethod
    def add(self):
        raise NotImplemented
    def getchildren(self):
        pass
class Point(Graphic):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def draw(self):
        print(self)
    def add(self, graphic):
        raise TypeError
    def getchildren(self):
        raise TypeError
    def __str__(self):
        return "点(%s, %s)" % (self.x, self.y)
class Line(Graphic):
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2
    def draw(self):
        print(self)
    def add(self, graphic):
        raise TypeError
    def getchchildren(self):
        raise TypeError
    def __str__(self):
        return "线段[%s, %s]" % (self.p1, self.p2)
class Picture(Graphic):
    def __init__(self):
        self.children = []
    def add(self, graphic):
        self.children.append(graphic)
    def getchildren(self):
        return self.children
    def draw(self):
        print("-------复合图形-------")
        for g in self.children:
            g.draw()
        print("------END--------")
pic1 = Picture()
point = Point(2, 3)
pic1.add(point)
pic1.add(Line(Point(1, 2), Point(4, 5)))
pic1.add(Line(Point(0, 1), Point(2, 1)))
pic2 = Picture()
pic2.add(Point(-2, -1))
pic2.add(Line(Point(0, 0), Point(1, 1)))
pic = Picture()
pic.add(pic1)
pic.add(pic2)
pic.draw()
pic1.draw()
point.draw()