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Re: URIs in constraints, isBound, casting in eq

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Mon, 22 Nov 2004 18:47:26 +0000
Message-ID: <41A2343E.5010500@hp.com>
To: Dan Connolly <connolly@w3.org>
CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>



Dan Connolly wrote:
> On Mon, 2004-11-22 at 16:48 +0000, Seaborne, Andy wrote:
> [...]
> 
>>Yes - it is.  Maybe it shouldn't be, but the following is possible:
>>
>>    dc:title =~ /^http:/    # Test whether http URI
>>
>>so extension functions may take URIs as arguments.
> 
> 
> Whoah... I'm rushing to get out the door for Thanksgiving travel,

And have a good Thanksgiving.

> so apologies for lack of suggested replacement and such...
> but that sets off a huge use/mention RED FLAG, for me.

Point taken.  It is a pragmatic thing that people do.  Doesn't mean it is 
correct or the only way of doing it.  The use/mention in query isn't replacing 
RDF - it's graph matching here.

> 
> dc:title is a an RDF property, not a string.
> 
> We can introduce something ala log:uri if we want
> to do that sort of use/mention level-breaking:
> 
> 	WHERE dc:title log:uri ?TITLEURI
> 	AND ?TITLEURI =~ /^http:/

I'd prefer to reuse the function fn:string() from F&O that stringify's anything 
it's give as we already have a syntax for expressions.  I just had that implicit 
in the =~ operation.  On typed literals, it would be the lexical form.

	string(dc:title) =~ /^http:/

	Andy
Received on Monday, 22 November 2004 18:47:50 GMT

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