class ShortInputException(Exception):
    '''A user-defined exception class'''
    def __init__(self, length,atleast):
    Edited by LATEX80ubA Byte of Python第14章 异常
      Exception.__init__(self)
      self.length = length
      self.atleast = atleast

try:
    text = input('Enter something-->')
    if len(text) < 3:
    raise ShortInputException(len(text),3)
    #other work can continue as usual here
except EOFError:
    print('Why did you do an EOF on me')
except ShortInputException as ex:
    print('ShortInputException The input was {0} long, excepted\
    atleast {1}'.format(ex.length, ex.atleast))
else:
    print('No exception was raised.')

Create ch14_05_try_except.py