W3C home > Mailing lists > Public > public-rdf-dawg-comments@w3.org > March 2006

Re: Comment: don't use ? and $. Pick one. [OK?]

From: Pat Hayes <phayes@ihmc.us>
Date: Sun, 5 Mar 2006 21:14:47 -0800
Message-Id: <p06230911c031745661ac@[192.168.1.4]>
To: Elliotte Harold <elharo@metalab.unc.edu>
Cc: Dan Connolly <connolly@w3.org>, public-rdf-dawg-comments@w3.org

>On Sun, 2006-03-05 at 18:56 -0500, Elliotte Harold wrote:
>>  If there's a justification for using both $ and ? to represent
>>  variables, I haven't found it yet.
>
>The WG made that choice in the course of resolving the
>punctuationSyntax issue.
>  http://www.w3.org/2001/sw/DataAccess/issues#punctuationSyntax
>
>A number of design considerations were laid out in:
>Draft: open issues around '?' use.
>http://lists.w3.org/Archives/Public/public-rdf-dawg/2004OctDec/0160
>
>
>>   I haven't finished reading the spec
>>  yet, so I could be missing it; but just looking at the BNF, I don't
>>  think there's any significant difference.
>
>Indeed, there is none.
>
>>  If this is true, then I strongly urge the working group to pick one.
>>  personally I prefer the dollar sign. It's not a reserved character in
>>  URLs and it's already used to indicate variables in other languages such
>>  as PHP. However this isn't a strong preference. I could certainly live
>>  with a question mark.
>>
>>  However I feel having too makes the language pointlessly complex, much
>>  harder to read, and harder to learn. It increases the size of the spec,
>>  increases the size and complexity of the grammar, and reserves an extra
>>  character that must now be avoided.

Just a quick clarification: it does not reserve two characters, which 
is one of its strengths. If you have a variable name beginning with 
'?', then prefix it with '$', and vice versa. XML uses a similar 
trick with the single and double quote option, which allows quoted 
strings containing either single or double quote characters (but not 
both).

Pat Hayes
-- 
---------------------------------------------------------------------
IHMC		(850)434 8903 or (650)494 3973   home
40 South Alcaniz St.	(850)202 4416   office
Pensacola			(850)202 4440   fax
FL 32502			(850)291 0667    cell
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
Received on Monday, 6 March 2006 05:15:08 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:14:50 GMT