python面向对象入门实例(构造函数、方法调用)

#!/usr/bin/python 
# Filename: simplestclass.py 
 
class Person: 
    pass # An empty block 
 
p = Person() 
print p  

$ python simplestclass.py
<__main__.Person instance at 0xf6fcb18c>

#!/usr/bin/python 
# Filename: method.py 
 
class Person: 
    def sayHi(self): 
        print 'Hello, how are you?' 
 
p = Person() 
p.sayHi() 
 
# This short example can also be written as Person().sayHi()  

$ python method.py
Hello, how are you?
 

#!/usr/bin/python 
# Filename: class_init.py 
 
class Person: 
    def __init__(self, name): 
        self.name = name 
    def sayHi(self): 
        print 'Hello, my name is', self.name 
 
p = Person('Swaroop') 
p.sayHi() 
 
# This short example can also be written as Person('Swaroop').sayHi()  

$ python class_init.py
Hello, my name is Swaroop

#!/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 '(Initializing %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 
 
        Person.population -= 1 
 
        if Person.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 
 
swaroop = Person('Swaroop') 
swaroop.sayHi() 
swaroop.howMany() 
 
kalam = Person('Abdul Kalam') 
kalam.sayHi() 
kalam.howMany() 
 
swaroop.sayHi() 
swaroop.howMany()  

$ python objvar.py
(Initializing Swaroop)
Hi, my name is Swaroop.
I am the only person here.
(Initializing Abdul Kalam)
Hi, my name is Abdul Kalam.
We have 2 persons here.
Hi, my name is Swaroop.
We have 2 persons here.
Abdul Kalam says bye.
There are still 1 people left.
Swaroop says bye.
I am the last one.