Re: Property copying final issues

On Jan 29, 2013, at 21:36 , Gregg Kellogg <gregg@greggkellogg.net> wrote:

> We're almost done with the conversation on property copying, but I don't think we've quite converged yet.
> 
> The current draft of the spec has the following rules:
> 
> Rule: pattern-copy
>  ?subject rdfa:copy ?target . ?target a rdfa:Pattern; ?predicate ?object
>  => 
>  ?subject ?predicate ?object .
>  except -- ?predicate = rdf:type and ?object = rdfa:Pattern.
> 
> Rule: clean-copy:
> ?subject rdfa:copy ?target => remove ?subject rdfa:copy ?target
> 
> Rule: clean-pattern:
>  ?subject a rdfa:Pattern; ?predicate ?object => remove ?subject ?predicate ?object
> 
> There are several problems with this that the original statement had addressed:
> 
> * The pattern-copy uses a form of pattern not used in any other specs, whereas the original closely followed the rule language in RDFS.
> 

I think it is better to use the same style indeed.

> * The clean-copy rule removes every use of rdfa:copy, not just those which actually reference a defined pattern.
> 
> * The clean-pattern rule removes all patterns, even if they're not referenced.
> 
> It may be that these rules are easier to understand than the originals, but they mean different things; we should be clear on what we want the semantics to be.
> 
> Should we remove every use of rdfa:copy, even if it doesn't reference a pattern? I think this may be a problem if we do.
> 

For the record: in my own implementation that was based on the discussion we had back then, only the properly used rdfa:copy triples are removed. And I think this is fine; as Niklas said, if we keep those, it signals that something is missing...

And to Niklas: I would be against introducing yet another flag. It is a minor thing and we should only have one well specified behaviour in my view.

> Should we remove every pattern, even if it is not referenced? This could be a problem, but I could imaging using a "library" of patterns which may or may not be used by a specific document, and not wanting the patterns to survive.
> 

Again, my implementation does not remove them, ie, that was our discussion result back then. I do not have a very strong feeling about this one; but it seems to be more consistent with the previous (rdfa:copy) approach to restrict removal only to those that are really used.

> I think we need to finally resolve these issues, and have some final rules in place before we can agree to publish.
> 

Yes. As Manu said, Gregg, why don't you reproduce the rules you had in the document and we call it a day? The feature is 'at risk', and the 'at risk' may also yield input from the community on this (do we want to call these questions out explicitly in the 'at risk' note? Maybe we should.)

Ivan


> Gregg Kellogg
> gregg@greggkellogg.net
> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
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