实例查找属性的顺序:

类属性 > 数据描述符 > 实例属性 > 非数据描述符 > __getattr__

类属性>数据描述符>实例属性

class Str:    def __get__(self, instance, owner):        print("执行: __get__")    def __set__(self, instance, value):        print("执行: __set__")    def __delete__(self, instance):        print("执行: __delete__")class A:    name = Str()    def __init__(self):        self.name = "mm"a = A()A.name = "maotai_class"  # 添加类属性print(a.name) # 1.优先打印类属性 2.其次打印数据描述符 3.最后打印实例属性

实例属性>非数据描述符

class Str:    def __get__(self, instance, owner):        print("执行: __get__")    # def __set__(self, instance, value):    #     print("执行: __set__")    # def __delete__(self, instance):    #     print("执行: __delete__")class A:    name = Str()a = A()a.name = "maotai"print(a.__dict__)--{'name': 'maotai'}

class Str:    def __get__(self, instance, owner):        print("执行: __get__")    def __set__(self, instance, value):        print("执行: __set__")    # def __delete__(self, instance):    #     print("执行: __delete__")class A:    name = Str()a = A()a.name = "maotai"print(a.__dict__)--执行: __set__{}

非数据描述符>找不到

class A:    def __getattr__(self, item):        print("触发__getattr__")a = A()a.xxx # 触发__getattr__