[Python-Dev] PEP 463: Exception-catching expressions

[Chris Angelico]

On Fri, Feb 28, 2014 at 10:33 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:
>
> On 28 Feb 2014 05:56, "Chris Angelico" <rosuav at gmail.com> wrote:
>>
>> On Fri, Feb 28, 2014 at 6:36 AM, Glenn Linderman <v+python at g.nevcal.com>
>> wrote:
>> > +1
>> >
>> >     f() except ((TypeError, AttributeError): "No value")
>> >
>> > is a nice extension to the idea of
>> >
>> >     value = expr except (
>> >         Exception1: default1,
>> >         Exception2: default2,
>> >         Exception3: default3,
>> >    )
>> >
>> > Which I've liked since I first saw it, as it neatly solves handling
>> > multiple
>> > except clauses.
>>
>> You can already list multiple exception types. The definition of the
>> exception_list is exactly as per the try/except statement (bar the
>> 'as' keyword, which I would love to see implemented some day).
>
> Note that this example is covering the deferred case of multiple except
> clauses that resolve to different values, not the already handled case of
> multiple exception types that resolve to the same value.

The "nice extension" to that notation is already handled, though.

> Anyway, even if you choose not to switch the parenthesis requirement in PEP,
> it should at least make the "colon as in dict display, not as in suite
> introduction" comparison, and note this as an alternative proposal for the
> required parentheses.

Hmm. Not sure that it really helps, but okay. Will word something up.

ChrisA