[Tutor] How to raise error without the stack trace

[Karim]

Le 26/11/2011 15:20, Rich Lovely a écrit :
> On 26 November 2011 11:41, Steven D'Aprano<steve at pearwood.info>  wrote:
>> Hugo Arts wrote:
>>> On Sat, Nov 26, 2011 at 11:16 AM, Karim<kliateni at gmail.com>  wrote:
>>>> Hello,
>>>>
>>>> I want to fire my own exception without having the (useful but ugly in my
>>>> case) stack trace display.
>>>>
>>>> How to modify a Exception type class for that purpose which looks like:
>>>>
>>>> classs MyError(Exception):
>>>>       pass
>>>>
>>>> Cheers
>>>> Karim
>>>>
>>> The stack trace is what happens when an exception is uncaught. You
>>> don't need to modify it. What you want to do is catch the exception,
>>> print it, then, depending on whether you can recover from the error,
>>> possibly do a sys.exit(-1).
>> If you can recover from the error, by all means catch the exception. That's
>> what exceptions are for!
>>
>> But otherwise, please think very, very, VERY carefully before printing an
>> error message and exiting. This is normally the wrong thing to do.
>>
>> Stack traces are useful. They show you exactly what has gone wrong, and
>> where (although sadly not why!). There is very little worse than a "helpful"
>> programmer who turns a sensible, useful stack trace into a useless, stupid
>> message:
>>
>> "An error has occurred"
>>
>> or worse.
>>
>> Perhaps the most sensible example I can think of is this:
>>
>>
>> def main():
>>     # your code goes here...
>>
>>
>> if __name__ == '__main__':
>>     try:
>>         main()
>>     except KeyboardInterupt:
>>         # Not an error, so no need for a stack trace.
>>         print "operation cancelled by user"
>>         sys.exit(1)
>>
>>
>> and that's it. Any other exception is a bug in your code, and so the stack
>> trace should be printed so the user can report it.
>>
>>
>> --
>> Steven
>>
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> Although there's nothing wrong with taking the stack trace and
> cleaning it up - perhaps dumping it to a logfile, using the Traceback
> module.  Asking your users to send a file (or even automating the
> process in your except: block is much more user friendly than
> expecting them to be able to copy and paste from a (potentially
> hidden, for GUI apps) console.  It also ensures you get the entire
> stack trace, rather than just what they think is useful.
>

Sorry,

I did not explain myself clearly. I Kow when I fired it because it is in 
code like:

If not value:
     raise MyError('You did wrong here!')

And in that case I did not want the stack trace because I know perfectly 
where the message is triggered.

To avoid stack trace in try/except I use print(e) then sys.exit(1) or 
return 1.
I just wanted to know if it is possible to control the stack trace 
display when
raising my own exception.

And sure, Steven I hate message like 'Problem happens exitting...'.
My error messages are acute I just wanted to filter the stack trace.

Thanks all for you answers.
Cheers
Karim