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Re: what does @instanceof refer to

From: Mark Birbeck <mark.birbeck@formsPlayer.com>
Date: Thu, 20 Sep 2007 15:08:49 +0100
Message-ID: <a707f8300709200708q7c1d3efek2b26cbea437e24ff@mail.gmail.com>
To: "Niklas Lindström" <lindstream@gmail.com>
Cc: "Ben Adida" <ben@adida.net>, RDFa <public-rdf-in-xhtml-tf@w3.org>

Hi Niklas,

Sorry for the stray "regards" in there, which may have made the post
look like it ended! :) I had actually replied to your comments inline.

Mark

On 20/09/2007, Mark Birbeck <mark.birbeck@formsplayer.com> wrote:
> Niklas,
>
> I will reply to Ben as well, but I'd like to reply to you first
> because you put the issue in such a compact way! The problem is that
> what started out meaning one thing (@class, then @role, then
> @instanceof) has been co-opted to behave in a different way, due to
> the re-introduction of chaining.
>
> The argument is therefore *not* what is the 'correct' interpretation
> of @instanceof, but rather should the re-introduction of chaining back
> into RDFa affect the behaviour of rdf:type? In other words, we're
> looking for a change here.
>
> Regards,
>
> Mark
>
> On 20/09/2007, Niklas Lindström <lindstream@gmail.com> wrote:
> >
> > Hi Ben!
> >
> > +1. I fully agree with your reasoning.
> >
> > You've actually formulated my exact opinion. I began scribbling a
> > draft about this a couple of days ago, but time eluded me. You made
> > the point much more clearly though. I think the key is that the
> > presence of @rel is so significant.
> >
> > [ A note though: while we view @instanceof as sugar for a child
> > element, it may also generate a bnode by itself, so it isn't exactly
> > equivalent.
>
> It is!
>
> The way that <link> and <meta> on a child element were defined was
> that they created a bnode if no @about was present. Historically, this
> originated from the idea that this:
>
>   <div>
>     <link rel="my:property" href="http://resource.com" />
>     ...
>   </div>
>
> was equivalent to this:
>
>   <div my:property="http://resource.com">
>     ...
>   </div>
>
> In other words, the <link> and <meta> values 'attached' themselves to
> the item identified by the parent element, and *not* to the current
> in-scope resource (for example, that last @about) up the tree).
>
> By extension, therefore these are equivalent:
>
>   <div>
>     <link rel="rdf:type" href="http://resource.com" />
>     ...
>   </div>
>
>   <div rdf:type="http://resource.com">
>     ...
>   </div>
>
> and of course, all that is being proposed with @instanceof is that this:
>
>   <div rdf:type="http://resource.com">
>     ...
>   </div>
>
> can be abbreviated to this:
>
>   <div instanceof="http://resource.com">
>     ...
>   </div>
>
> A while ago we were forced to drop this 'link and meta anywhere'
> feature because different browsers did different things with the
> mark-up--most notably, Firefox moved the elements from the body to the
> head, so the parser would have no context information.
>
> But I don't think that means that we should abandon all of the
> 'logical' work that went into arriving at this syntax; I think it's a
> key part of the general 'approach', and there is no reason that it
> cannot be incorporated into future versions of XHTML+RDFa.
>
>
>
> > The further effect of it (in my interpretation) is that
> > when both @about and @rel are absent, *the effect of* an @about with a
> > bnode is also implied.
>
> As described above, that has always been there.
>
>
> > Just as @rel without @resource or equivalent
> > has the effect of a bnode @resource... ]
>
> @rel is unique in this respect though. I personally don't like it,
> since it creates an intermediate object between the current element
> and all child elements, and in that it is a little odd. (I.e., there
> is no correspondence with the DOM.) But since other people seem to
> think this is useful I've kept quiet about it, although I've not found
> a situation where it is so useful that it warrants making the mark-up
> less clear.
>
> But although I can live with @rel doing these things--creating these
> ghostly child bnodes--I'm having trouble going along with the same
> thing for @instanceof.
>
> Regards,
>
> Mark
>
> --
>   Mark Birbeck, formsPlayer
>
>   mark.birbeck@formsPlayer.com | +44 (0) 20 7689 9232
>   http://www.formsPlayer.com | http://internet-apps.blogspot.com
>
>   standards. innovation.
>


-- 
  Mark Birbeck, formsPlayer

  mark.birbeck@formsPlayer.com | +44 (0) 20 7689 9232
  http://www.formsPlayer.com | http://internet-apps.blogspot.com

  standards. innovation.
Received on Thursday, 20 September 2007 14:09:14 UTC

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