自定义异常

异常通常直接或间接的从Exception类派生

  
    

   
     
   
     #
   
     ! /usr/bin/python
   
     

   
     

   
     import
   
      sys,os


   
     class
   
      MyError(Exception):
 
   
     def
   
      
   
     __init__
   
     (self,value):
 self.value 
   
     =
   
      value
 
   
     def
   
      
   
     __str__
   
     (self):
 
   
     return
   
      repr(self.value)


   
     try
   
     :
 f 
   
     =
   
      open(
   
     '
   
     myfile.txt
   
     '
   
     )


   
     except
   
      IOError, (errno,strerror):
 
   
     print
   
      
   
     "
   
     I/O error(%s): %s
   
     "
   
      
   
     %
   
     (errno,strerror)


   
     #
   
     raise NameError, "Just for test! "
   
     

   
     raise
   
      MyError, 
   
     "
   
     my error is raised!
   
     "
  
    

 

the result:

  
    

   
     
   
     Traceback (most recent call last):
 File 
   
     "
   
     test.py
   
     "
   
     , line 
   
     18
   
     , 
   
     in
   
      <module
   
     >
   
     
 raise MyError, 
   
     "
   
     my error is raised!
   
     "
   
     
__main__.MyError: 'my error is raised
   
     !
   
     '