标签：ict date ret 改变 一行代码 包含 答案 color 思考
Python设计模式之适配器模式，代码，思考等
# -*- coding: utf-8 -*- # author：baoshan class Computer: def __init__(self, name): self.name = name def __str__(self): return ‘the {} computer‘.format(self.name) def execute(self): return ‘executes a program‘ class Synthesizer: def __init__(self, name): self.name = name def __str__(self): return ‘the {} synthesizer‘.format(self.name) def play(self): return ‘is playing an electronic song‘ class Human: def __init__(self, name): self.name = name def __str__(self): return ‘{} the human‘.format(self.name) def speak(self): return ‘says hello‘ class Adapter: def __init__(self, obj, adapted_methods): self.obj = obj self.__dict__.update(adapted_methods) def __str__(self): return str(self.obj) def main(): objects = [Computer(‘Asus‘)] synth = Synthesizer(‘moog‘) objects.append(Adapter(synth, dict(execute=synth.play))) human = Human(‘Bob‘) objects.append(Adapter(human, dict(execute=human.speak))) for i in objects: print(‘{} {}‘.format(str(i), i.execute())) if __name__ == ‘__main__‘: main()
代码输出：
the Asus computer executes a program the moog synthesizer is playing an electronic song Bob the human says hello
------------------------------------------------------------------------------------------
我们设法使得Human和Synthesizer类与客户端所期望的接口兼容，且无需改变它们的源代码。这太棒了!
这里有一个为你准备的挑战性练习，当前的实现有一个问题，当所有类都有一个属性name时，以下代码会运行失败。
for i in objects: print(‘{}‘.format(i.name))
首先想想这段代码为什么会失败?虽然从编码的角度来看这是有意义的，但对于客户端代码来说毫无意义，客户端不应该关心“适配了什么”和“什么没有被适配”这类细节。我们只是想提供一个统一的接口。该如何做才能让这段代码生效?
思考一下如何将未适配部分委托给包含在适配器类中的对象。
答案如下：
将适配器类更改如下，增加一行代码
class Adapter: def __init__(self, obj, adapted_methods): self.obj = obj self.__dict__.update(adapted_methods) self.name = obj.name def __str__(self): return str(self.obj)
然后在main函数中获取对应的name，如下
def main(): objects = [Computer(‘Asus‘)] synth = Synthesizer(‘moog‘) objects.append(Adapter(synth, dict(execute=synth.play))) human = Human(‘Bob‘) objects.append(Adapter(human, dict(execute=human.speak))) for i in objects: print(‘{} {}‘.format(str(i), i.execute())) print(‘{}‘.format(i.name)) if __name__ == ‘__main__‘: main()
输出结果如下：
the Asus computer executes a program Asus the moog synthesizer is playing an electronic song moog Bob the human says hello Bob
参考自：《精通Python设计模式》
标签：ict date ret 改变 一行代码 包含 答案 color 思考
原文地址：https://www.cnblogs.com/zhzhang/p/11287648.html
