【Python046--魔法方法：描述符】

class MyDecriptor:
    def __get__(self,instance,owner):
        #打印查看描述符的get，set,delete方法中各个参数的含义
        print("getting...",self,instance,owner)

    def __set__(self,instance,value):
        print("setting...",self,instance,value)

    def __delete__(self,instance):
        print("deleteing...",self,instance)

class Test:
    #把特殊类MyDecriptor的实例指派给Test类的x属性
    x = MyDecriptor()

执行结果：
>>> test = Test()
>>> test.x
getting... <__main__.MyDecriptor object at 0x10a2186d8> <__main__.Test object at 0x10a208f60> <class ‘__main__.Test‘>
>>> test
<__main__.Test object at 0x10a208f60>
>>> Test
<class ‘__main__.Test‘>

‘‘‘
|--由打印出来的getting...，可以看出来，参数self是MyDecriptor的对象(<__main__.MyDecriptor object at 0x10a2186d8>)
|--参数instance是Test的对象(<__main__.Test object at 0x10a208f60>)
|--参数owner是Test的本类自己(<class ‘__main__.Test‘>)
|--具体可由对象test打印出来的内容，和Test类打印出来的内容得到验证
|--set和delete同理
‘‘‘
>>> test.x = "X-man"
setting... <__main__.MyDecriptor object at 0x10a2186d8> <__main__.Test object at 0x10a208f60> X-man
>>> del test.x
deleteing... <__main__.MyDecriptor object at 0x10a2186d8> <__main__.Test object at 0x10a208f60>
>>>