>>>
class a:
... foo=100
...
>>>
dir(a)
['__doc__',
'__module__',
'foo']
>>>
vars(a)
{'__module__':
'__main__',
'foo': 100,
'__doc__': None}
>>> b=
a()
>>>
dir(b)
['__doc__',
'__module__',
'foo']
>>>
vars(b)
{}上面看出，经典类a中貌似没有__dict__属性。为什么可以作为vars()函数的参数呢？
>>> vars(1)
Traceback (most recent call last):
File "", line 1, in
TypeError: vars() argument must have __dict__ attribute
提示必须有__dict__属性。
下面看出：dir的参数是新式类或其对象时，返回值包括__dict__属性。
>>>
class c(object):
... foo=200
...
>>>
dir(c)
['__class__',
'__delattr__',
'__dict__',
'__doc__',
'__format__',
'__getattribute__',
'__hash__',
'__init__',
'__module__',
'__new__',
'__reduce__',
'__reduce_ex__',
'__repr__',
'__setattr__',
'__sizeof__',
'__str__',
'__subclasshook__',
'__weakref__',
'foo']
>>>
vars(c)
dict_proxy({'__dict__':
'__dict__' of 'c' objects>, '__module__': '__main__', 'foo': 200, '__weakref__': '__weakref__' of 'c' objects>, '__doc__': None})
>>> d=c()
>>> dir(d)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'foo']
>>> vars(d)
{}
>>> c.
__dict__
dict_proxy({'__dict__':
'__dict__' of 'c' objects>, '__module__': '__main__', 'foo': 200, '__weakref__': '__weakref__' of 'c' objects>, '__doc__': None})
>>> d.__dict__
{}
>>> a.__dict__
{'__module__': '__main__', 'foo': 100, '__doc__': None}
>>> b.__dict__
{}
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