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

[Guido van Rossum]

> This looks like an issue that potentially deserves more community
> feedback, so I'm ripping it out and starting a new thread: should
> exception objects be treated as mutable as exceptions get caught and
> re-raised?

(A new thread in python-dev hardly counts as "community feedback".)

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().

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