python中的属性认识

class T(object):    name ='windy'        def bark(self):        passt = T()print dir(t)#['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__get__', #'__getattribute__', '__hash__', '__init__', '__module__', '__new__',  #'__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__',  #'__str__', '__subclasshook__', '__weakref__', 'bark', 'name']  复制代码

属性分为两类，一是python自带的，例如__calss__,__hash__

实例调用未定义的属性

实例直接调用未定义的属性时，程序会抛出异常。

class TestA(object):        pass        testA = TestA()    print testA.name    #AttributeError: 'TestC' object has no attribute 'name'    print testA.bark()  #AttributeError: 'TestC' object has no attribute 'name'复制代码

实例访问属性的顺序

t先到t.__dict__ 搜寻属性key,如果找不到，又会到T.__dict__中搜寻属性key，如果还找不到，就会到T父类的__dict__去搜寻，都没有搜寻到就是会抛出一个exception

class T(object):    name ='windy'    def bark(self):        pass    def __get__(self, instance, owner):        return '__get__windy'        t = T()print t.__dict__  #{}空字典print T.__dict__ t.name = 'windy'print t.__dict__  #{'name': 'windy'}#{'__module__': '__main__', 'bark': 
    
     ,#'__dict__': 
     
      , '__get__': 
      
       , '__weakref__': 
       
        , '__doc__': None, 'name': 'windy'}复制代码