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Re: Simplification of scopes section (see also ISSUE-148)

From: Holger Knublauch <holger@topquadrant.com>
Date: Fri, 13 May 2016 13:37:33 +1000
To: public-data-shapes-wg@w3.org
Message-ID: <a53f97ed-b8fd-03d9-9254-99057d02eacc@topquadrant.com>
On 13/05/2016 13:22, Karen Coyle wrote:
> On 5/12/16 5:51 PM, Holger Knublauch wrote:
>> I agree the editorial arrangement of these subsections is unhelpful, and
>> I have aligned the nesting with this commit:
>> https://github.com/w3c/data-shapes/commit/fd044c834960c791cc1740509224057d03057567 
>> The naming and syntax issue had been raised before as
>> https://www.w3.org/2014/data-shapes/track/issues/148
>> I would find it very unfortunate if we switched to another syntax that
>> hard-codes these few scope types and then requires a completely
>> different syntax for the general scope mechanism of the extension
>> mechanism. Such decisions drive up implementation costs significantly,
>> and also require the reader of SHACL to look at a rather arbitrary
>> collection of predicates.
> Yet the current design takes a very different approach between node 
> and class-based scopes, which are "hard coded", and the remaining 
> scopes, which are subclasses of sh:Shape. We have:
> ex:PersonShape
>     a sh:Shape ;
>     sh:scopeNode ex:Alice .
> and
> ex:PropertyScopeExampleShape
>     a sh:Shape ;
>     sh:scope [
>         a sh:PropertyScope ;
>         sh:predicate ex:knows ;
>     ] .
> So the inconsistency is already there, to the inconvenience of the user.

Yes, the inconsistency is already there, but I would say for the 
convenience of the user. In particular the case of sh:scopeClass will be 
so common, that having to go through an intermediate object would be 
quite redundant. Less so for sh:scopeNode, but who can anticipate the 

>  Also, what would be the object of ex:MyShape
>> sh:allObjectsScope triples?
> I'd like to think more about the "all objects" "all subjects" -- I'm 
> having trouble thinking of them as scopes in this same sense; I almost 
> think they'd fit into the constraints functional area. Do we have use 
> cases for those? that would help.

No, I don't have use cases for these. They are candidates for deletion 
IMHO, in which case we may end up with only 4 scopes to "hard-code", 
which sounds more realistic to me.

Does anyone have use cases for "all subjects" and "all objects" scopes?

Received on Friday, 13 May 2016 03:38:07 UTC

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