使用super函数

__metaclass__ = type #确定使用新式类

class Bird:
def __init__(self):
self.hungry = True

def eat(self):
if self.hungry:
print 'Aaaah...'
self.hungry = False
else:
print 'No,thanks!'

class SongBird(Bird):
"""docstring for SongBird"""
def __init__(self):
super(SongBird, self).__init__()
self.sound = 'Squawk!'

def sing(self):
print self.sound

class Bird(object):
def __init__(self):
self.hungry = True

def eat(self):
if self.hungry:
print 'Aaaah...'
self.hungry = False
else:
print 'No,thanks!'

class SongBird(Bird):
"""docstring for SongBird"""
def __init__(self):
super(SongBird, self).__init__()
self.sound = 'Squawk!'

def sing(self):
print self.sound