class Foo:

     def __init__(self,x):

         self.x=x

     def __getattr__(self, item):

         print('执行的是我')

         # return self.__dict__[item]

 f1=Foo(10)

 print(f1.x)

 f1.xxxxxx #不存在的属性访问，触发__getattr__

 回顾__getattr__

 class Foo:

     def __init__(self,x):

         self.x=x

     def __getattribute__(self, item):

         print('不管是否存在,我都会执行')

 f1=Foo(10)

 f1.x

 f1.xxxxxx

 __getattribute__

 #_*_coding:utf-8_*_

 __author__ = 'Linhaifeng'

 class Foo:

     def __init__(self,x):

         self.x=x

     def __getattr__(self, item):

         print('执行的是我')

         # return self.__dict__[item]

     def __getattribute__(self, item):

         print('不管是否存在,我都会执行')

         raise AttributeError('哈哈')

 f1=Foo(10)

 f1.x

 f1.xxxxxx

 #当__getattribute__与__getattr__同时存在,只会执行__getattrbute__,除非__getattribute__在执行过程中抛出异常AttributeError

 二者同时出现

 #_*_coding:utf-8_*_

 __author__ = 'Linhaifeng'

 format_dict={

     'nat':'{obj.name}-{obj.addr}-{obj.type}',#学校名-学校地址-学校类型

     'tna':'{obj.type}:{obj.name}:{obj.addr}',#学校类型:学校名:学校地址

     'tan':'{obj.type}/{obj.addr}/{obj.name}',#学校类型/学校地址/学校名

 }

 class School:

     def __init__(self,name,addr,type):

         self.name=name

         self.addr=addr

         self.type=type

     def __repr__(self):

         return 'School(%s,%s)' %(self.name,self.addr)

     def __str__(self):

         return '(%s,%s)' %(self.name,self.addr)

     def __format__(self, format_spec):

         # if format_spec

         if not format_spec or format_spec not in format_dict:

             format_spec='nat'

         fmt=format_dict[format_spec]

         return fmt.format(obj=self)

 s1=School('oldboy1','北京','私立')

 print('from repr: ',repr(s1))

 print('from str: ',str(s1))

 print(s1)

 '''

 str函数或者print函数--->obj.__str__()

 repr或者交互式解释器--->obj.__repr__()

 如果__str__没有被定义,那么就会使用__repr__来代替输出

 注意:这俩方法的返回值必须是字符串,否则抛出异常

 '''

 print(format(s1,'nat'))

 print(format(s1,'tna'))

 print(format(s1,'tan'))

 print(format(s1,'asfdasdffd'))

 date_dic={

     'ymd':'{0.year}:{0.month}:{0.day}',

     'dmy':'{0.day}/{0.month}/{0.year}',

     'mdy':'{0.month}-{0.day}-{0.year}',

 }

 class Date:

     def __init__(self,year,month,day):

         self.year=year

         self.month=month

         self.day=day

     def __format__(self, format_spec):

         if not format_spec or format_spec not in date_dic:

             format_spec='ymd'

         fmt=date_dic[format_spec]

         return fmt.format(self)

 d1=Date(2016,12,29)

 print(format(d1))

 print('{:mdy}'.format(d1))

 自定义format练习

 #_*_coding:utf-8_*_

 __author__ = 'Linhaifeng'

 class A:

     pass

 class B(A):

     pass

 print(issubclass(B,A)) #B是A的子类,返回True

 a1=A()

 print(isinstance(a1,A)) #a1是A的实例

 issubclass和isinstance

class Foo:

    '我是描述信息'

    pass

print(Foo.__doc__)

class Foo:

    '我是描述信息'

    pass

class Bar(Foo):

    pass

print(Bar.__doc__) #该属性无法继承给子类

该属性无法被继承

#!/usr/bin/env python

# -*- coding:utf-8 -*-

class C:

    def __init__(self):

        self.name = ‘SB'

lib/aa.py

from lib.aa import C

obj = C()

print obj.__module__  # 输出 lib.aa，即：输出模块

print obj.__class__      # 输出 lib.aa.C，即：输出类