python函数property例解

函数property的基本功能就是把类中的方法当作属性来访问，下面以一个有意思的例子介绍一下：

假如有一只猫，它忘了它喜欢吃什么，下面看看我们如何治好它吧

原代码： #运行环境 python2.6.5

class Cat(object):

def __init__(self,food):

self.food=food

def eat(self):

return self.food

def say(self):

if 'im_func' in dir(self.eat):

print "I forgot what to eat,Mybe %s" % self.food

else:

print "Miao...,I want to eat fish!"

if __name__ == "__main__":

tim=Cat('Stone')

tim.say()

运行后，这只猫说“I forgot what to eat,Mybe Stone”

看来是真有问题了

来个小改动吧：

class Cat(object):

def __init__(self,food):

self.food=food

@property

def eat(self):

return self.food

def say(self):

if 'im_func' in dir(self.eat):

print "I forgot what to eat,Mybe %s" % self.food

else:

print "Miao...,I want to eat fish!"

if __name__ == "__main__":

tim=Cat('Stone')

tim.say()

这回这只猫记起来了

“Miao...,I want to eat fish!”

看来情况出在@property这个装饰器上

假如我们把@property去掉

在后边加一行代码

#!/usr/bin/python

#-*-utf-8-*-

class Cat(object):

def __init__(self,food):

self.food=food

@property

def eat(self):

return self.food

def say(self):

if 'im_func' in dir(self.eat):

print "I forgot what to eat,Mybe %s" % self.food

else:

print "Miao...,I want to eat fish!"

if __name__ == "__main__":

tim=Cat('Stone')

tim.say()

try:

tim.eat="Is fish deliciout?"

print tim.eat

except:

print "^^,Fish is so nice"

<div>

</div>

输出：

I forgot what to eat,Mybe Stone
Is fish deliciout?

现在我们把装饰器@property加上去

输出：

Miao...,I want to eat fish!
^^,Fish is so nice

可能这个例子也不是很适合解释这个例子，不过应该还是蛮生动的吧

从网上了解到，用@property装饰成的属性在2.6无法赋值

为了过渡期的兼容性，需要我们自己来配置setter

#!/usr/bin/python

#-*-utf-8-*-

class C(object):

def __init__(self,x):

self.__x=x

@property

def foo(self):

return self.__x

@foo.setter

def foo(self,value):

self.__x=value

@foo.deleter

def foo(self):

del self.__x

if __name__ == "__main__":

c=C(10)

print c.foo

c.foo=12

print c.foo

输出

本站仅提供存储服务，所有内容均由用户发布，如发现有害或侵权内容，请点击举报。