模板方法模式

模板方法模式

不知道你有没有注意过，我们实现某个业务功能，在不同的对象会有不同的细节实现， 以前说过策略模式, 策略模式是将逻辑封装在一个类(提到的文章中的Duck)中，然后使用委托的方式解决。 模板方法模式的角度是：把不变的框架抽象出来，定义好要传入的细节的接口. 各产品类的公共的行为 会被提出到公共父类，可变的都在这些产品子类中

示例

import six

class AlooDish(object):
    def get_ingredients(self,):
        self.ingredients = {}

    def prepare_vegetables(self,):
        for item in six.iteritems(self.ingredients):
            print("take {0} {1} and cut into smaller pieces".format(item[0],item[1]))
        print("cut all vegetables in small pieces")

    def fry(self,):
        print("fry for 5 minutes")

    def serve(self,):
        print("Dish is ready to be served")

    def cook(self,):
        self.get_ingredients()
        self.prepare_vegetables()
        self.fry()
        self.serve()

class AlooMatar(AlooDish):
    def get_ingredients(self,):
        self.ingredients = {'aloo':"1 Kg",'matar':"1/2 kg"}

    def fry(self,):
        print("wait 10 min")

class AlooPyaz(AlooDish):
    def get_ingredients(self):
        self.ingredients = {'aloo':"1 Kg",'pyaz':"1/2 kg"}

aloomatar = AlooMatar()
aloopyaz = AlooPyaz()
print("*******************  aloomatar cook")
aloomatar.cook()
print("******************* aloopyaz cook")
aloopyaz.cook()

在上面的例子中，我们将公共的步骤抽象出来，放在父类中，而将不同的部分，实现在子类中。

输出结果为

*******************  aloomatar cook
take aloo 1 Kg and cut into smaller pieces
take matar 1/2 kg and cut into smaller pieces
cut all vegetables in small pieces
wait 10 min
Dish is ready to be served
******************* aloopyaz cook
take pyaz 1/2 kg and cut into smaller pieces
take aloo 1 Kg and cut into smaller pieces
cut all vegetables in small pieces
fry for 5 minutes
Dish is ready to be served