[Tutor] class questions

[Payal]

Thanks a lot Eike for the code snippet. I got the idea now.

With warm regards,
-Payal
-- 


On Sat, Jun 26, 2010 at 10:41:59PM +0200, Eike Welk wrote:
> Hello Payal!
> 
> On Saturday June 26 2010 19:05:16 Payal wrote:
> > Can we say that our own exception classes have only maybe a doc-string
> > and pass, nothing more?
> 
> No, you let the exception transport the information that you need for handling 
> the error. This is an exception that I use to transport user visible error 
> messages in a compiler, that I write as a hobby:
> 
> 
> class UserException(Exception):
>     '''Exception that transports user visible error messages.'''
>     def __init__(self, message, loc=None, errno=None):
>         Exception.__init__(self)
>         self.msg = message
>         self.loc = loc
>         self.errno = errno
> 
>     def __str__(self):
>         if self.errno is None:
>             num_str = ''
>         else:
>             num_str = '(#%s) ' % str(self.errno) 
>         return 'Error! ' + num_str + self.msg + '\n' + str(self.loc) + '\n'
> 
>     def __repr__(self):
>         return self.__class__.__name__ + str((self.msg, self.loc, 
>                                               self.errno))
> 
> It contains:
>     self.msg : The error message
>     self.loc : An object encoding the location of the error in the program's
>                text. Together with the file name and the text.
>     self.errno : An integer to identify the error, for the test framework.
> 
> That said; the expression's type and the error message are often sufficient to 
> handle the error.
> 
> 
> Eike.