Python适配器模式代码实现解析
Python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》
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