摘要.
隨意的風 2016-12-01 15:49:45 
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注：每周一到周五都会进行相关Python基础知识更新，欢迎大家提宝贵的意见
python 语言提供了一种挂钩，使得开发者能够很方便的编写出通用代码，他们使用的不是普通实例的属性，@property 方法和描述符，而是使用的是 python 的魔术方法
__gettattr__、__getattribute__和__setattr__, 他们属于动态行为。
>>> class TEST(object):
def __init__(self):
self.value = 1
def __getattr__(self, name):
value = 'Value for %s' % name
setattr(self, name, value)
return value
testobj = TEST()
print('---:',testobj.__dict__)
{'__methods__':'Value for __methods__','__members__':'Value for __members__','value': 1}
>>> print(testobj.__dict__)
{'__methods__':'Value for __methods__','__members__':'Value for __members__','value': 1}
print(testobj.attr)
'Value for attr'print(testobj.__dict__)
{'__methods__':'Value for __methods__','__members__':'Value for __members__','value': 1,'attr':'Value for attr'}
总结：
__gettattr__: 如果某个类定义了这个方法，并且在该类的对象的字典中又找不到相应的属性时候，那么次方法会被调用。
__getattribute__: 不管对象的字典中有没有找到对应的属性，都会调用
__setattr__: 无论是直接赋值还是通过内置的 setattr 函数赋值，都会调用
**********还有一点需要住的是__**getattribute__和__setattr__方法中访问实例属性的时候，应该直接通过 super() 来做，避免无线递归。**********
def __getattribute__(self, name): print("__getattribute__() is called name =", name)return object.__getattribute__(self, name)def __getattr__(self, name): print("__getattr__() is called name =", name)return name + " from getattr"def __get__(self, instance, owner): print("__get__() is called instance = {} owner = {}".format(instance, owner))if __name__ == '__main__': print('-----------存在的属性：__getattribute__------------\n') print('-----------不存在的属性__getattribute__ ---》 __getattr__------------\n') print('----------类直接访问成员（实现了__get__的类）都会先经过__get__函数-------------\n') print('-----------对象直接访问成员（实现了__get__的类）都会先经过__get__函数------------\n') print('----------类把直接访问成员（实现了__get__的类）中存在的属性：__get__ --> __getattribute__ -------------\n') print('-----------对象直接访问成员（实现了__get__的类）中不存在的属性：__get__ --> __getattribute__ -->__getattr__ ------------\n')```
[https://blog.csdn.net/Windgs_YF/article/details/53422478?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-15.control&dist_request_id=&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-15.control](https://blog.csdn.net/Windgs_YF/article/details/53422478?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-15.control&dist_request_id=&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-15.control)
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