Re-raising exceptions with modified message

[Alex Popescu]

On Jul 6, 4:20 am, Christoph Zwerschke <c... at online.de> wrote:
> Alex Popescu wrote:
> > Probably the simplest solution would be to create a new exception and
> > wrapping the old one and the additional info. Unfortunately, this
> > may have a huge impact on 3rd party code that was catching the
> > original exception. So, I think you should create an utility
> > factory-like function that is either creating a new exception
> > instance as the one caught and with the additional information,
>
> Right, I have gone with that (see the example with the PoliteException
> class somewhere below).
>
> > or an utility that knows how to modify the caught exception according
> > to its type.
>
> I guess you mean something like this (simplified):
>
> except Exception, e:
>      if getattr(e, 'reason'):
>          e.reason += "sorry"
>      else:
>          e.message += "sorry"
>
> The problem is that these attribute names are not standardized and can
> change between Python versions. Not even "args" is sure, and if a class
> has "message" it does not mean that it is displayed. Therefore I think
> the first approach is better.
>
> > In the first case you will need somehow to tell to the new instance
> > exception the real stack trace, because by simply raising
> > a new one the original stack trace may get lost.
>
> Yes, but thats a different problem that is easy to solve.
>

Yeah maybe for a python guy, but I am a newbie. I would really
appreciate if you can show in this thread how this can be done in
Python.

tia,

./alex
--
.w( the_mindstorm )p.

PS: sorry for reposting, but it looks like my previous message hasn't
gone through :-(.