[Python-Dev] "as" keyword woes

[Guido van Rossum]

On Sun, Dec 7, 2008 at 1:06 PM, Paul Boddie <paul at boddie.org.uk> wrote:
> On Sat Dec 6 21:29:09 CET 2008, Guido van Rossum wrote:
>>
>> On Sat, Dec 6, 2008 at 11:38 AM, Warren DeLano <warren at delsci.com>
>> wrote:
>> > As someone somewhat knowledgable of how parsers work, I do not
>> > understand why a method/attribute name "object_name.as(...)" must
>> > necessarily conflict with a standalone keyword " as ".  It seems to me
>> > that it should be possible to unambiguously separate the two without
>> > ambiguity or undue complication of the parser.
>>
>> That's possible with sufficiently powerful parser technology, but
>> that's not how the Python parser (and most parsers, in my experience)
>> treat reserved words. Reserved words are reserved in all contexts,
>> regardless of whether ambiguity could arise.
>
> Just a quick aside from someone who merely lurks on this list: in SQL, it's
> quite possible to use keywords in a fashion similar to that desired by the
> inquirer, and it's actually possible to double-quote keywords and use them as
> names for things. I'm not advocating more complicated parsing technology for
> any Python implementation, but I think it's pertinent to point out that the
> technology isn't particularly obscure.

>From my experience with SQL, it's nearly as bad as Python in that
every single one of the 200+ reserved words in a typical
implementation cannot be used as a name in any context without using
double quotes. While the double-quote escape is handy (especially
given there are so many obscure reserved words) this is not exactly
what the OP wanted -- they would have to say x."as"('float'), except
using some other notation instead of double quotes. Having to escape
it completely kills the OP's claim that 'as' is "simplest and most
elegant".

-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)