使用super函数

<<Python基础编程>>

__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

继承新式类（例如object），就不用添加__metaclass__ = type了

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