__setattr__,__getattr__

class A(object):

    def __setattr__(self, key, value):
        self.__dict__[key] = value

    def __getattr__(self, name):
        return "xxx"

#实例化.
obj = A()

#1. 调用getattr方法 返回结果：xxx
print(obj.namd22e )

#2. 调用getattr方法,返回结果：xxx
print(obj.dd)

#3. 打印内置属性，为空.{}
print(obj.__dict__)

#4. 给属性赋值 name 为key , helleworld 为值value.
obj.name = "helloworld"

#5. 打印内置属性,存在一个{"name":"helleworld"}
print(obj.__dict__)

#6. 打印name属性，结果为 helloworld
print(obj.name)