#!/usr/bin/env python

# -*- coding: utf-8 -*-

"""http://ginstrom.com/scribbles/2008/11/06/generic-adapter-class-in-python/"""

#适配器模式 adapter pattern

#把一个类的结构变成客户端所期待的另外一种借口

#使原来因为接口不兼容的两个类现在可以协同工作

#分为两种

#1.类的适配器：适配器继承自已经实现的类

#2.对象适配器：适配器容纳一个它包裹的类的实例

#本代码实现的是第二种

class Dog(object):

def __init__(self):

self.name = "Dog"

#add a common attribute for all objects

self.age = 1

def bark(self):

return "woof!"

class Cat(object):

def __init__(self):

self.name = "Cat"

self.age = 2

def meow(self):

return "meow!"

class Human(object):

def __init__(self):

self.name = "Human"

self.age = 3

def speak(self):

return "'hello'"

class Car(object):

def __init__(self):

self.name = "Car"

self.age = 4

def make_noise(self, octane_level):

return "vroom{0}".format("!" * octane_level)

class Adapter(object):

"""

Adapts an object by replacing methods.

Usage:

dog = Dog

dog = Adapter(dog, dict(make_noise=dog.bark))

>>> objects = []

>>> dog = Dog()

>>> objects.append(Adapter(dog, make_noise=dog.bark))

>>> cat = Cat()

>>> objects.append(Adapter(cat, make_noise=cat.meow))

>>> human = Human()

>>> objects.append(Adapter(human, make_noise=human.speak))

>>> car = Car()

>>> car_noise = lambda: car.make_noise(3)

>>> objects.append(Adapter(car, make_noise=car_noise))

>>> for obj in objects:

... print('A {} goes {}'.format(obj.name, obj.make_noise()))

A Dog goes woof!

A Cat goes meow!

A Human goes 'hello'

A Car goes vroom!!!

"""

def __init__(self, obj, **adapted_methods):

"""We set the adapted methods in the object's dict"""

self.obj = obj

self.__dict__.update(adapted_methods)

#执行过后

#self.obj = obj

#self.make_noise = obj.some_method

def __getattr__(self, attr):

"""All non-adapted calls are passed to the object"""

#getattr(obj, attr)

#把attr当作一个变量去处理

#return self.obj.attr

#调用obj自身的attr的值

return getattr(self.obj, attr)

def main():

objects = []

dog = Dog()

objects.append(Adapter(dog, make_noise=dog.bark))

print objects[-1].__dict__

#obj.obj = dog

#obj.make_noice() = dog.bark()

#是之前实例化之后的dog的bark()

cat = Cat()

objects.append(Adapter(cat, make_noise=cat.meow))

human = Human()

objects.append(Adapter(human, make_noise=human.speak))

car = Car()

objects.append(Adapter(car, make_noise=lambda: car.make_noise(3)))

for obj in objects:

print("A {0} goes {1}, its age is {2}".format(obj.name, obj.make_noise(), obj.age))

if __name__ == "__main__":

main()

### OUTPUT ###

# A Dog goes woof!

# A Cat goes meow!

# A Human goes 'hello'

# A Car goes vroom!!!