python之一个类如何从另一个类继承

一个类如何继承另一个类？我正在尝试通过以下示例来实现它:

class parents(object): 
      def __init__(self,dim_x, dim_y, nameprefix, sequence_number): 
          if not isinstance(dim_x, (int, float, long)): 
             raise TypeError("Dimension in x must be a number") 
          else: 
             self.sizex=str(int(dim_x)) 
          if not isinstance(dim_y, (int, float, long)): 
             raise TypeError("Dimension in y must be a number") 
          else: 
             self.sizey=str(int(dim_y)) 
          if not isinstance(nameprefix, string_types): 
              raise TypeError("The name prefix must be a string") 
          else: 
              self.prefix=nameprefix 
          if not isinstance(sequence_number, (int, float, long)): 
             raise TypeError("The sequence number must be given as a number") 
          else: 
             self.sqNr=str(int(sequence_number)) 

我希望 child 类从 parents 类继承 prefix 和 sqNr

class child(parents): 
      def __init__(self,image_path='/vol/'): 
         self.IMG_PATH=image_path 
         self.ref_image=self.prefix+'_R_'+self.sqNr 
         logger.debug('Reference image: %s', self.ref_image) 

并使用以下行运行它，但我收到一条错误消息:

>>> p=parents(300, 300, 'Test',0 ) 
>>> p.prefix 
'Test' 
>>> c=child(p) 
Traceback (most recent call last): 
  File "<stdin>", line 1, in <module> 
  File "<stdin>", line 4, in __init__ 
AttributeError: 'child' object has no attribute 'prefix' 

我不明白我的实现有什么问题，有什么建议吗？

请您参考如下方法:

child 需要为 parents 获取所有参数，并将它们一起传递。您通常不会将父类(super class)实例传递给子类；那是组合，而不是继承。

class child(parents): 
    def __init__(self, dim_x, dim_y, nameprefix,  
                 sequence_number, image_path='/vol/'): 
        super(child, self).__init__(dim_x, dim_y, nameprefix,  
                                    sequence_number) 
        self.IMG_PATH = image_path 
        ... 

这被称为:

c = child(300, 300, 'Test', 0) 

您不需要创建parents 实例，直接创建child。

请注意，根据 style guide ，类名实际上应该是 Parent 和 Child。