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Re: Value testing: implementing str()

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Mon, 21 Feb 2005 09:10:13 +0000
To: "'RDF Data Access Working Group'" <public-rdf-dawg@w3.org>
Message-ID: <20050221091013.GB28229@login.ecs.soton.ac.uk>

On Sun, Feb 20, 2005 at 07:20:32 +0000, Andy Seaborne wrote:
> >>2/ str(bNode) is an evaluation error
> >
> >
> >Is it out of the question to get a string with the same form as a N3 bNode
> >back? eg _:a. I'm not sure I'd argue for that, but I think that rejecting
> >all solutions which feature str(?x) where ?x binds to a bNode will be
> >inconvient and supprising in some cases.
> 
> Would the str(bNode) => "" regardless of label be useful?  It avoids
> rejecting the solution or requiring a sprinkling of
> 
>   isBlank(?x) || str(?x) ...
> 
> to change the sense of ?x being a bNode.

Ah, I think I misunderstood the sense of "evaluation error" I took that to
mean that str(?x) where ?x is a bNode will reject that solution. If
isBlank(?x) || str(?x) will always succeed I dont think this is so much of
an issue. Its a question for users though, really.
 
> Exposing the internal bNode label seems inappropriate (and, as the label has
> no meaning except to distinguish bNodes) meaningless.  Otherwise str() and 
> isBlank() could be used to find a bNode again :-)

I wasn't thinking it would be the internal name, more like the name we
serialise to in CONSTRUCT with returned bNodes.
 
> BTW - does it say somewhere that || and && only evaluate the RHS if the LHS
> is false/true respectively?

I dont remeber seeing any mention of shortcutting.

- Steve
Received on Monday, 21 February 2005 09:10:17 GMT

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