[Python-Dev] Re: Rationale for sum()'s design?

[Nicolas Fleury]

Nick Coghlan wrote:
> Guido van Rossum wrote:
>> No, no, no! NO! Never catch a general exception like that and replace
>> it with one of your own. That can cause hours of debugging pain later
>> on when the type error is deep down in the bowels of the += operation
>> (or perhaps deep down inside something *it* invoked).
> 
> 
> Ouch. Obviously, I hadn't thought about that. . .
> 
> Wasn't there a concept floating around some time ago to support 
> exception chaining, so additional context information could be added to 
> a thrown exception, without losing the location of the original problem?

Like that?

try :
     (...)
except Exception, exception:
     # Keep the current exception stack and add information to exception.
     raise Exception(
         'Additional exception info... :\n' +
         sys.exc_info()[0].__name__ + ': ' +
         str(exception)), None, sys.exc_info()[-1]

I made for myself a reraise function that I use a lot for that purpose, 
but it has some limitations.  A standard way to do it would be great.

Regards,
Nicolas