Python类的定义与使用

 #! /usr/bin/python

 # Filename:objvar.py

 class Person:

     '''Represents a person.'''

     population = 0

     def __init__(self, name):

         ''' Initializes the person's data. '''

         self.name = name

         print '(Initializeing %s)' % self.name

         # When this person is created, he/she adds to the population

         Person.population += 1

     def __del__(self):

         ''' I am dying. '''

         print '%s says bye.' % self.name

         self.__class__.population -= 1

         if self.__class__.population == 0:

             print 'I am the last one.'

         else:

             print 'There are still %d people left.' % Person.population

     def sayHi(self):

         ''' Greeting by the person.

         Really, that's all it does. '''

         print 'Hi, my name is %s.' % self.name

     def howMany(self):

         ''' Prints the current population. '''

         if Person.population == 1:

             print 'I am the only person here.'

         else:

             print 'We have %d persons here.' % Person.population

 # The definion of class is end

 zjw = Person('zjw')

 zjw.sayHi()

 zjw.howMany()

 lbz = Person('lbz')

 lbz.sayHi()

 lbz.howMany()

 zjw.sayHi()

 zjw.howMany()