[Python-Dev] Mutable exceptions? (was Re: PEP 293, Codec Error Handling Callbacks)

[Guido van Rossum]

> > I'd say definitely.  Code like this looks reasonable to me:
> > 
> >   def some_function(arg):
> >     try:
> >       call_some_other_function(arg)
> >     except SomeExpectedExceptionClass, obj:
> >       obj.add_context(arg)
> >       raise
> > 
> > Then some outer piece of code catches exceptions and produces a
> > traceback augmented by information added by various calls to
> > add_context().
> 
> So, if add_context() changes any exception attribute that was
> originally specified in the constructor and is thus part of
> the args attribute, should this change be reflected in the
> args attribute?

Usually yes, but that's up to the class that defines add_context().

--Guido van Rossum (home page: http://www.python.org/~guido/)