Re: shapes-ISSUE-192 (Are filters shapes?) - final questions

On 4/11/2016 2:20, Karen Coyle wrote:
>
>
> On 11/2/16 10:53 PM, Holger Knublauch wrote:
>>
>>
>> On 3/11/2016 14:36, Karen Coyle wrote:
>>>
>>>
>>> On 11/2/16 5:20 PM, Holger Knublauch wrote:
>>>>
>>>>
>>>> On 3/11/2016 0:48, Karen Coyle wrote:
>>>>> As decided at the meeting:
>>>>>
>>>>> On 10/28/16 9:39 AM, Karen Coyle wrote:
>>>>>> *QUESTION 1: What does it mean for a target to be "processed" as a
>>>>>> value? It's the term "processed" here that is problematic. 
>>>>>> Perhaps an
>>>>>> example would help, and then we could tweak the language.
>>>>>
>>>>> Proposed: The target of a shape that is the value of another shape
>>>>> MUST be ignored.
>>>>
>>>> This isn't correct. This would also mean that target must be ignored
>>>> here:
>>>>
>>>> ex:PersonShape
>>>>     sh:property [
>>>>         sh:predicate ex:address ;
>>>>         sh:shape ex:AddressShape ;
>>>>     ] .
>>>>
>>>> ex:AddressShape
>>>>     sh:targetClass ex:Address .
>>>>
>>>> I have tried to explain before that this is a matter of context, 
>>>> and it
>>>> only is ignored at validation time, not always.
>>>
>>> The spec has to define that context, and so far it doesn't. Please
>>> show an example of a target that would be ignored, and I will try to
>>> find appropriate wording.
>>
>> See the example above. Yes, we could put an elaborated example like this
>> together with example instance data and validation results. The problem
>> is that this is coming a bit early in the document - why should the
>> first example about targets be one that ignores targets. I also honestly
>> don't think such a corner case deserves so much space. I think we could
>> even delete the "Targets MUST be ignored..." paragraph because it
>> already follows as an implication from elsewhere. See the first sentence
>> "A target provides *one way* to specify potential focus nodes...". Other
>> ways include explicitly referencing a shape via sh:shape. So what about
>> deleting the paragraph and adding something along the lines of what Eric
>> suggested last night, to elaborate on other ways of finding focus nodes
>> such as API calls?
>
> Holger, you have misunderstood my question. I am not asking for such 
> an example to be added to the spec. I am asking for the example so 
> that I can consider better wording. You say that the example above is 
> one that should NOT be ignored. I am asking for an example of one that 
> SHOULD be ignored, that illustrates the context you have cited.

In the example above, the sh:targetClass statement is

- ignored if the AddressShape is reached as part of the sh:shape statement
- not ignored if the whole data graph is validated, i.e. the "standard 
way" of using SHACL

So if the shape is reached via sh:shape then the system does not test 
whether the given value of ex:address is also an instance of ex:Address 
(class). It could for example also be an untyped resource. sh:target 
never behaves like a constraint. (filterShape does).

HTH
Holger


>
> kc
>
>>
>> Anyway, now that I have given you an example, can you now rephrase the
>> paragraph about ignoring the target?
>>
>> Overall, we seem to continue to struggle with a different mindset about
>> the role of the spec here. I believe you want it to be longer and more
>> instructive, while currently it's rather compact and just mentions the
>> facts. You do not like this, but my viewpoint remains that this document
>> is not a tutorial.
>>
>> Holger
>>
>>
>>
>>>
>>> kc
>>>
>>>>
>>>>>
>>>>> (Alternate: The target *in* a shape... - I'm not sure what 
>>>>> language we
>>>>> are using for the various components of shapes. It could be "The
>>>>> target that is a component of a shape ..." Any of those would be ok
>>>>> with me as long as we are consistent.)
>>>>>
>>>>>>
>>>>>> *QUESTION 2: Does "are" here mean "MUST"? (This is a question
>>>>>> throughout
>>>>>> the document, actually, wherever "are" is used in this way. 
>>>>>> Perhaps we
>>>>>> can decide once for all.)
>>>>>
>>>>>
>>>>> Yes, MUST must be used here.
>>>>
>>>> I have switched to MUST.
>>>>
>>>> https://github.com/w3c/data-shapes/commit/06cd60457ec3448d7ca578c4aa3df324bea846f0 
>>>>
>>>>
>>>>
>>>>
>>>> Could we close this ticket now?
>>>>
>>>> Holger
>>>>
>>>>
>>>>
>>>
>>
>>
>>
>

Received on Thursday, 3 November 2016 23:51:35 UTC