python发生继承时 __dict__属性

class LazyDB():
    def __init__(self, exist=6) -> None:
        self.exists=exist
        print('Initilized called')
    
    # def __getattr__(self, name):
    #     value='V for %s'%name
    #     self.__dict__[name]=value
    #     return value
    

class LoggingLazyDB(LazyDB):
    def __getattr__(self, name):
        value='Child V for %s'%name
        self.__dict__[name]=value
        print('father __dict__', super().__dict__)
        return value

data2 = LoggingLazyDB()
data2.foo
print('After child:', data2.__dict__)

输出：

Initilized called
father __dict__ {'exists': 6, 'foo': 'Child V for foo'}
After child: {'exists': 6, 'foo': 'Child V for foo'}

 

可以看出继承时子类实例中的__dict__属性其实和父类共用，子类改变后父类也改变，这和一些博客宣称的不同