基于Python __dict__与dir()的区别详解

#!/usr/bin/python
# -*- coding: utf-8 -*-
class A(object):
  class_var = 1
  def __init__(self):
    self.name = 'xy'
    self.age = 2

  @property
  def num(self):
    return self.age + 10

  def fun(self):pass
  def static_f():pass
  def class_f(cls):pass

if __name__ == '__main__':#主程序
  a = A()
  print a.__dict__  #{'age': 2, 'name': 'xy'}  实例中的__dict__属性
  print A.__dict__  
  '''
  类A的__dict__属性
  {
  '__dict__': <attribute '__dict__' of 'A' objects>, #这里如果想深究的话查看参考链接5
  '__module__': '__main__',        #所处模块
  'num': <property object>,        #特性对象 
  'class_f': <function class_f>,     #类方法
  'static_f': <function static_f>,    #静态方法
  'class_var': 1, 'fun': <function fun >, #类变量
  '__weakref__': <attribute '__weakref__' of 'A' objects>, 
  '__doc__': None,            #class说明字符串
  '__init__': <function __init__ at 0x0000000003451AC8>}
  '''

  a.level1 = 3
  a.fun = lambda :x
  print a.__dict__ #{'level1': 3, 'age': 2, 'name': 'xy','fun': <function <lambda> at 0x>}
  print A.__dict__ #与上述结果相同

  A.level2 = 4
  print a.__dict__ #{'level1': 3, 'age': 2, 'name': 'xy'}
  print A.__dict__ #增加了level2属性

  print object.__dict__
  '''
  {'__setattr__': <slot wrapper '__setattr__' of 'object' objects>, 
  '__reduce_ex__': <method '__reduce_ex__' of 'object' objects>, 
  '__new__': <built-in method __new__ of type object at>, 
  等.....
  '''

print dir(A)
'''
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'age', 'class_f', 'class_var', 'fun', 'level1', 'level2', 'name', 'num', 'static_f']
'''
a_dict = a.__dict__.keys()
A_dict = A.__dict__.keys()
object_dict = object.__dict__.keys()
print a_dict 
print A_dict 
print object_dict 
'''
['fun', 'level1', 'age', 'name']

['__module__', 'level2', 'num', 'static_f', '__dict__', '__weakref__', '__init__', 'class_f', 'class_var', 'fun', '__doc__']

['__setattr__', '__reduce_ex__', '__new__', '__reduce__', '__str__', '__format__', '__getattribute__', '__class__', '__delattr__', '__subclasshook__', '__repr__', '__hash__', '__sizeof__', '__doc__', '__init__']
'''

#因为每个类都有一个__doc__属性，所以需要去重，去重后然后比较
print set(dir(a)) == set(a_dict + A_dict + object_dict) #True