Python: Decorator Pattern

 

DuDecorator.py

# 装饰模式 Decorator  Pattern
import six  # https://pypi.org/project/six/
from abc import ABCMeta


@six.add_metaclass(ABCMeta)
class Abstract_Coffee(object):

    def get_cost(self):
        pass

    def get_ingredients(self):
        pass

    def get_tax(self):
        return 0.1 * self.get_cost()


class Concrete_Coffee(Abstract_Coffee):

    def get_cost(self):
        return 1.00

    def get_ingredients(self):
        return '咖啡'


@six.add_metaclass(ABCMeta)
class Abstract_Coffee_Decorator(Abstract_Coffee):

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

    def get_cost(self):
        return self.decorated_coffee.get_cost()

    def get_ingredients(self):
        return self.decorated_coffee.get_ingredients()


class Sugar(Abstract_Coffee_Decorator):

    def __init__(self, decorated_coffee):
        Abstract_Coffee_Decorator.__init__(self, decorated_coffee)

    def get_cost(self):
        return self.decorated_coffee.get_cost()

    def get_ingredients(self):
        return self.decorated_coffee.get_ingredients() + ', 糖果'


class Milk(Abstract_Coffee_Decorator):

    def __init__(self, decorated_coffee):
        Abstract_Coffee_Decorator.__init__(self, decorated_coffee)

    def get_cost(self):
        return self.decorated_coffee.get_cost() + 0.25

    def get_ingredients(self):
        return self.decorated_coffee.get_ingredients() + ', 牛奶'


class Vanilla(Abstract_Coffee_Decorator):

    def __init__(self, decorated_coffee):
        Abstract_Coffee_Decorator.__init__(self, decorated_coffee)

    def get_cost(self):
        return self.decorated_coffee.get_cost() + 0.75

    def get_ingredients(self):
        return self.decorated_coffee.get_ingredients() + ', 香草'

　　

main.py

调用：

# 装饰模式 Decorator  Pattern
myCoffee = DuDecorator.Concrete_Coffee()
print('Geovin Du买材料: '+myCoffee.get_ingredients()+
   '; geovindu付费用: '+str(myCoffee.get_cost())+'; 涂聚文交营业税 = '+str(myCoffee.get_tax()))

myCoffee = DuDecorator.Milk(myCoffee)
print('Geovin Du买材料: '+myCoffee.get_ingredients()+
   '; geovindu付费用: '+str(myCoffee.get_cost())+'; 涂聚文交营业税 = '+str(myCoffee.get_tax()))

myCoffee = DuDecorator.Vanilla(myCoffee)
print('Geovin Du买材料: '+myCoffee.get_ingredients()+
   '; geovindu付费用: '+str(myCoffee.get_cost())+'; 涂聚文交营业税 = '+str(myCoffee.get_tax()))

myCoffee = DuDecorator.Sugar(myCoffee)
print('Geovin Du买材料: '+myCoffee.get_ingredients()+
   '; geovindu付费用: '+str(myCoffee.get_cost())+'; 涂聚文交营业税 = '+str(myCoffee.get_tax()))

　　

输出：

Geovin Du买材料: 咖啡; geovindu付费用: 1.0; 涂聚文交营业税 = 0.1
Geovin Du买材料: 咖啡, 牛奶; geovindu付费用: 1.25; 涂聚文交营业税 = 0.125
Geovin Du买材料: 咖啡, 牛奶, 香草; geovindu付费用: 2.0; 涂聚文交营业税 = 0.2
Geovin Du买材料: 咖啡, 牛奶, 香草, 糖果; geovindu付费用: 2.0; 涂聚文交营业税 = 0.2