| QVT expressivity [message #1064432] |
Wed, 19 June 2013 05:00  |
 Skander Turki
Messages: 128
Registered: July 2009 |
Senior Member |
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Hi,
I wanted to ask some questions about the expressivity of QVT that seems to me to be a little bit limited compared to other M2M languages (I may be wrong):
1- In defining a domain, in QVT, it seems we can only select one object of one type (c: UML::Class) we cannot for example select all tuples (c1:UMLClass, c2:UMLClass) as a single domain. Of course we can declare two distinct domains for each element, but if we could make a first filtering on the (c1, c2) couples, we could reduce the number of candidate tuples for the rule. If we could write something like:
checkonly domain
source c1:UML::Class,
source c2:UML::Class:
{
...
when{
-- domain-level pre-condition
c1<>c2;
}
};
....
when{
-- relation-level pre-condition
}
2- All the examples from the QVT spec and from the MediniQVT tutorials use meta-models that are designed following a special pattern:
"the contained elements (for example classes) have a reference (myPackage) to the container (package)."
No example is given with a container that has a collection of references (non eOpposite) to its contained elements. How this is delt with in QVT?
Thanks
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| Re: QVT expressivity [message #1064437 is a reply to message #1064432] |
Wed, 19 June 2013 05:16  |
Ed Willink
Messages: 3446
Registered: July 2009 |
Senior Member |
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Hi Skander
IMHO you have hit on an area where the QVTr (and QVTc and QVTo)
specifications are at best vague. I think that an additional 'rooting'
condition needs to be available for specification by the invoking
context, and a much clearer semantics of collection matching is required.
I would tentatively expect that if you apply a transformation defined on
C=>D to a Collection(C) that the result will be a Collection(D).
In UMLX where I tried to support collection matching, you would specify
Collection(C)[2] as the input type so that the transformation would be
applied to all distinct permutations of two Cs.
I currently have student working on realizing a QVTr to qVTc to QVTu to
QVTm to QVTi to OCL to Java chain. I expect that the precision of
Collection matching is something that we get to in about a year's time.
Regards
Ed Willink
On 19/06/2013 11:00, Skander Turki wrote:
> Hi,
> I wanted to ask some questions about the expressivity of QVT that
> seems to me to be a little bit limited compared to other M2M languages
> (I may be wrong):
> 1- In defining a domain, in QVT, it seems we can only select one
> object of one type (c: UML::Class) we cannot for example select all
> tuples (c1:UMLClass, c2:UMLClass) as a single domain. Of course we can
> declare two distinct domains for each element, but if we could make a
> first filtering on the (c1, c2) couples, we could reduce the number of
> candidate tuples for the rule. If we could write something like:
>
> checkonly domain source c1:UML::Class,
> source c2:UML::Class:
> {
> ...
> when{
> -- domain-level pre-condition
> c1<>c2;
> }
> };
> ....
> when{ -- relation-level pre-condition
> }
>
> 2- All the examples from the QVT spec and from the MediniQVT tutorials
> use meta-models that are designed following a special pattern:
> "the contained elements (for example classes) have a reference
> (myPackage) to the container (package)."
> No example is given with a container that has a collection of
> references (non eOpposite) to its contained elements. How this is delt
> with in QVT?
>
>
> Thanks
>
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