详解Python中类的定义与使用

类顾名思义，就是一类事物、或者叫做实例，它用来描述具有共同特征的一类事物。我们在python中声明类的关键词是class，类还有功能和属性，属性就是这类事物的特征，而功能就是它能做什么，也是就是方法或者函数。我们仍然用例子来说明问题。

目标：

　　1.类的定义

　　2.父类，子类定义，以及子类调用父类

　　3.类的组合使用

　　4.内置功能

1.类的定义

代码如下：

    #!/usr/bin/env python
    #coding:utf8


    class Hotel(object):
      """docstring for Hotel"""
      def __init__(self, room, cf=1.0, br=15):
        self.room = room
        self.cf = cf
        self.br = br

      def cacl_all(self, days=1):
        return (self.room * self.cf + self.br) * days

    if __name__ == '__main__':
      stdroom = Hotel(200)
      big_room = Hotel(230, 0.9)
      print stdroom.cacl_all()
      print stdroom.cacl_all(2)
      print big_room.cacl_all()
      print big_room.cacl_all(3)

2.父类、子类以及调用父类

代码如下：

    #!/usr/bin/env python
    # -*- coding: utf-8 -*-

    # 父类
    class AddBook(object):
      def __init__(self, name, phone):
        self.name = name
        self.phone = phone

      def get_phone(self):
        return self.phone

    # 子类，继承
    class EmplEmail(AddBook):
      def __init__(self, nm, ph, email):
        # AddBook.__init__(self, nm, ph) # 调用父类方法一
        super(EmplEmail, self).__init__(nm, ph) # 调用父类方法二
        self.email = email

      def get_email(self):
        return self.email

    # 调用
    if __name__ == "__main__":
      Detian = AddBook('handetian', '18210413001')
      Meng = AddBook('shaomeng', '18210413002')

      print Detian.get_phone()
      print AddBook.get_phone(Meng)

      alice = EmplEmail('alice', '18210418888', 'alice@xkops.com')
      print alice.get_email(), alice.get_phone()

3.类的组合使用

代码如下：

    #!/usr/bin/env python
    # -*- coding: utf-8 -*-

    '''
    1.class类的组合使用
    2.手机、邮箱、QQ等是可以变化的（定义在一起），姓名不可变（单独定义）。
    3.在另一个类中引用
    '''

    class Info(object):
      def __init__(self, phone, email, qq):
        self.phone = phone
        self.email = email
        self.qq = qq

      def get_phone(self):
        return self.phone

      def update_phone(self, newphone):
        self.phone = newphone
        print "手机号更改已更改"

      def get_email(self):
        return self.email


    class AddrBook(object):
      '''docstring for AddBook'''
      def __init__(self, name, phone, email, qq):
        self.name = name
        self.info = Info(phone, email, qq)


    if __name__ == "__main__":
      Detian = AddrBook('handetian', '18210413001', 'detian@xkops.com', '123456')
      print Detian.info.get_phone()
      Detian.info.update_phone(18210413002)
      print Detian.info.get_phone()
      print Detian.info.get_email()

4.内置功能(函数（）加与不加的区别）

代码如下：

    #!/usr/bin/env python
    #coding:utf8

    class Books(object):
      def __init__(self, title, author):
        self.title = title
        self.author = author

      def __str__(self):
        return self.title

      def __repr__(self):
        return self.title

      def __call__(self):
        print "%s is written by %s" %(self.title, self.author)


    if __name__ == '__main__':
      pybook = Books('Core Python', 'Wesley')
      print pybook
      pybook()

    #!/usr/bin/env python
    #coding:utf8

    class Number(object):
      """Custum object
      add/radd -> +; 
      sub/rsub -> -;
      mul/rmul -> *;
      div/rdiv -> /;
      """
      def __init__(self, number):
        self.number = number

      def __add__(self, other):
        return self.number + other    

      def __radd__(self, other):
        return self.number + other

      def __sub__(self, other):
        return self.number - other

      def __rsub__(self, other):
        return other - self.number


      def __gt__(self, other):
        if self.number > other:
          return True
        return False


    if __name__ == '__main__':
      num = Number(10)
      print num + 20
      print 30 + num
      print num - 5
      print 11 - num
      print num > 20

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