Exception Handling in Python 3

Steve Holden steve at holdenweb.com
Sun Oct 24 07:42:33 CEST 2010

On 10/24/2010 1:26 AM, Chris Rebert wrote:
>> I was somewhat surprised to discover that Python 3 no longer allows an
>> > exception to be raised in an except clause (or rather that it reports it
>> > as a separate exception that occurred during the handling of the first).
> <snip>
>> > What
>> > is the correct paradigm for this situation?
> There doesn't seem to be one at the moment, although the issue isn't
> very serious. Your Traceback is merely being made slightly longer/more
> complicated than you'd prefer; however, conversely, what if a bug was
> to be introduced into your exception handler? Then you'd likely very
> much appreciate the "superfluous" Traceback info.
> Your quandary is due to the unresolved status of the "Open Issue:
> Suppressing Context" in PEP 3141
> (http://www.python.org/dev/peps/pep-3134/ ). I guess you could start a
> discussion about closing that issue somehow.

You're right about the issue not being serious, (and about the possible
solution, though I don't relish a lengthy discussion on python-dev) but
it does seem that there ought to be some way to suppress that
__context__. From the user's point of view the fact that I am raising
AttributeError because of some implementation detail of __getattr__() is
exposing *way* too much information.

I even tried calling sys.exc_clear(), but alas that doesn't help :(

Steve Holden           +1 571 484 6266   +1 800 494 3119
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