什么是 python 构建器模式

class Item:
    # Item类提供水果的基础信息的抽象类
    def set_name(self):
        pass
 
    def packing(self):
        pass
 
    def set_price(self):
        pass
 
    def set_weight(self):
        pass
 
    def promotion_price(self):
        pass
 
 
class Pack:
    # Pack管理水果的包装方式
    def pack(self):
        pass
 
 
class box_pack(Pack):
    # box-pack采用盒装方式
    def pack(self):
        return "盒装"
 
 
class bag_pack(Pack):
    # bag-pack采用袋装方式
    def pack(self):
        return "袋装"
 
 
class Grape(Item):
    # 葡萄类
    def packing(self):
        wrap = box_pack()
        return wrap
 
    def set_price(self):
        grape_price = 18.0
        return grape_price
 
    def set_name(self):
        grape_name = "葡萄"
        return grape_name
 
    def set_weight(self):
        grape_weight = 2.5
        return grape_weight
 
    def promotion_price(self):
        return 28.99
 
 
class Hami_Melon(Item):
    # 哈密瓜类
    def packing(self):
        wrap = bag_pack()
        return wrap
 
    def set_price(self):
        hami_melon_price = 22.0
        return hami_melon_price
 
    def set_name(self):
        hami_melon_name = "哈密瓜"
        return hami_melon_name
 
    def set_weight(self):
        hami_melon_weight = 3.2
        return hami_melon_weight
 
    def promotion_price(self):
        return 39.99
 
 
class Orange(Item):
    # 橘子大类
    def packing(self):
        wrap = bag_pack()
        return wrap
 
    def set_price(self):
        pass
 
 
class Citrus(Orange):
    # 柑橘类
    def set_price(self):
        citrus_price = 12.5
        return citrus_price
 
    def set_name(self):
        citrus_name = "柑橘"
        return citrus_name
 
    def set_weight(self):
        citrus_weight = 2.6
        return citrus_weight
 
    def promotion_price(self):
        return 18.88
 
 
class Tangerine(Orange):
    # 冰橘类
    def set_price(self):
        tangerine_price = 13.0
        return tangerine_price
 
    def set_name(self):
        tangerine_name = "冰橘"
        return tangerine_name
 
    def set_weight(self):
        citrus_weight = 3.3
        return citrus_weight
 
    def promotion_price(self):
        return 26.66
 
 
class Menu:
    def __init__(self):
        self.items = []
 
    def AddItem(self, item):
        # 添加item，即添加参与促销活动的水果
        self.items.append(item)
 
    def ShowItems(self):
        # ShowItem，展示参与促销活动的水果清单
        print("-*-" * 5 + "限时促销清单" + "-*-" * 10)
        for item in self.items:
            print("◎Item：" + item.set_name() + " 包装：" + item.packing().pack() + " 原价：" + str(
                item.set_price()) + "元/千克" + " 重量：" + str(item.set_weight()) + "千克" + "\n        限时促销价：" +
                  str(item.promotion_price()) + "元!!!")
        print("-*-" * 5 + "限时促销清单" + "-*-" * 10)
 
 
class MenuBuilder:
    @staticmethod
    def PrepareMenu():
        # 构造清单，过程如下：
        menu = Menu()
        menu.AddItem(Grape())
        menu.AddItem(Citrus())
        menu.AddItem(Tangerine())
        menu.AddItem(Hami_Melon())
        return menu
 
 
if __name__ == '__main__':
    # 新建一个建造者
    menu_builder = MenuBuilder()
    # 建造促销活动的水果清单
    menu_object = menu_builder.PrepareMenu()
    # 展示参与促销活动的水果信息
    menu_object.ShowItems()