新手python求各位解答个简单的问题

代码如下

#! /usr/bin/env python
_metaclass_ = type

class bird:
def _init_(self):
self.hungry = True
def eat(self):
if self.hungry:
print 'I am hungry'
self.hungry = False
else:
print 'No,thanks'
class Songbird(bird):
def _init_(self):
super(Songbird, self)._init_()
self.sound = 'Squawk!'
def sing(self):
print self.sound

a = Songbird()
a.sing()
a.eat()
a.eat()

错误信息：

Traceback (most recent call last):
File "bird.py", line 21, in <module>
a.sing()
File "bird.py", line 18, in sing
print self.sound
AttributeError: Songbird instance has no attribute 'sound'

self

sound

sing

5 条回复 • 1970-01-01 08:00:00 +08:00

9hills

2013-09-21 14:54:47 +08:00

python里面是__init__
不是_init_

两个下划线

ybooty

2013-09-21 15:16:36 +08:00

@9hills 修改后
Traceback (most recent call last):
File "bird.py", line 20, in <module>
sb = Songbird()
File "bird.py", line 15, in __init__
super(Songbird, self).__init__()
TypeError: must be type, not classobj

ybooty

2013-09-21 15:29:34 +08:00

把super(Songbird, self).__init__() 改为 bird.__init()的方法就可以成功，为什么前者就出问题..

ybooty

2013-09-21 15:31:28 +08:00

问题已经解决

9hills

2013-09-21 20:18:58 +08:00

@ybooty
super() cannot be used with old-style class

Python定义类有两种方法，调用父类初始化函数也有两种方法。

class A: 这是旧的定义方法
class A(object): 所有的类必须有父类，也就是bird类必须这么定义： class bird(object):
这是新的定义方法，只有新类型的类才能用super来init