1 class ShortInputException(Exception): 2     def __init__(self, length, atleast): 3         Exception.__init__(self) 4         self.length = length 5         self.atleast = atleast 6          7 try: 8     s = raw_input('Enter something --> ') 9     10     if len(s) < 3 :11         raise ShortInputException(len(s), 3)12 except EOFError:13     print '\nWhy did you do an EOF on me?'14 except ShortInputException, x:15     print 'ShortInputException: The input was of length %d, \16           was expecting at least %d' % (x.length, x.atleast)17 else:18     print 'No exception was raised.'

x就是 ShortInputException的对象 这是python 2.6之前的语法 2.6之后建议使用 except ShortInputException as x: