[Python-ideas] except expression

[Ron Adam]

On 02/20/2014 07:31 AM, Chris Angelico wrote:
> On Fri, Feb 21, 2014 at 12:23 AM, Ron Adam<ron3200 at gmail.com>  wrote:
>> >The expression doesn't need to be just too terms, it could be something more
>> >complex.
>> >
>> >       (except KeyError: d1[key] or d2[key] or d3[key] or None)
>> >
>> >
>> >Would give the first dictionary lookup that doesn't raise KeyError or None.
>> >
>> >Because the exception paths and data paths don't overlap, they could be
>> >dictionaries containing exception instances and it would still work.
> Okay. I think I follow. The way to spell that in the current proposal is:
>
> d1[key] except KeyError: (d2[key] except KeyError: (d3[key] except
> KeyError: None))
>
> which is rather more verbose. On the other hand, the syntax you have
> requires magic around the 'or' keyword.
>
> ChrisA


Correct.  And it would need to be able to differentiate the normal use of 
'or' and the except 'or'.  Probably with braces in some way.

Ron