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Date: Sun, 12 Apr 2015 06:05:34 +1000
Subject: Re: try..except with empty exceptions
From: Chris Angelico <rosuav@gmail.com>
Cc: Python <python-list@python.org>
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On Sun, Apr 12, 2015 at 6:04 AM, Chris Angelico <rosuav@gmail.com> wrote:
> On Sun, Apr 12, 2015 at 4:49 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
>> On Apr 11, 2015 5:06 AM, "Steven D'Aprano"
>> <steve+comp.lang.python@pearwood.info> wrote:
>>>
>>> Yes, I agree that Python's behaviour here is better than the alternative.
>>> Having "except ()" catch nothing is consistent with the behaviour with
>>> other tuples, so I'm okay with that. But it still surprised me :-)
>>
>> There's another alternative that I haven't seen suggested yet. An empty
>> tuple could be considered an indication of a programming error and raise a
>> chained ValueError.
>
> Not really a lot of point. Just as with isinstance, an empty tuple
> simply matches nothing. Why go to the effort of rejecting it?

(At least, I assume you're not putting a literal empty tuple in. This
would be useful only in cases where the tuple is provided
dynamically.)

ChrisA