try..except with empty exceptions

[Chris Angelico]

On Sun, Apr 12, 2015 at 6:04 AM, Chris Angelico <rosuav at gmail.com> wrote:
> On Sun, Apr 12, 2015 at 4:49 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> On Apr 11, 2015 5:06 AM, "Steven D'Aprano"
>> <steve+comp.lang.python at 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