[sc34wg3] Explanation in TMCL?

Robert Cerny robert at cerny-online.com
Wed Jan 27 08:08:45 EST 2010

On Jan 26, 2010, at 6:47 PM, Lars Marius Garshol wrote:

> * Robert Cerny
>> or whether something like this is necessary:
>> tmcl:explanation isa tmcl:occurrence-type;
>>  has-datatype(xsd:string).
>> tmcl:constraint
>>  has-occurrence(tmcl:explanation, 0, *).
> Yes, this (except perhaps "0, 1", since presumably one explanation  
> is enough) looks better.

"0, *" because the explanation is a text in natural language and not  
everybody speaks English, so it should be possible to attach an  
explanation in English and one in French and so on.

> However, I think this is outside the scope of TMCL, so that it's  
> better if you define your own occurrence type.

I disagree that creating a useful validation report is outside the  
scope of constraint language. Overall it is just a minature change  
(note that my suggestion does not require TMQL) and will overall make  
TMCL more useable, because it will create better validation reports.  
It is not more than tmcl:comment or tmcl:see-also. Just that it is  
really useful :-)

> Note that something similar has already been proposed by me and  
> rejected by the committee: http://projects.topicmapslab.de/issues/1447

Hmm. I am having troubles understanding the rejection reason. No real  
notion of error? But what do we have constraints for then? Is there  
maybe some minutes of the meeting which explains the rejection in  
more depth? As a someone with a very strong practical orientation i  
think the suggestion is a good, just that i do not see the necessity  
to make it dependent on TMQL, since the error message can be  
presented together with the statement that violates the constraint.  
And this will already make a lot of sense. More sense than some  
generic blabla, which you can always fall back to if there is no  
custom error message for the constraint.


Robert Cerny

Software Development

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