[news.eclipse.modeling.gmf] Re: GMF mapping Audit Rules

["Christian W. Damus" <cdamus@xxxxxxxxxxxxx>]

Hi, Achilleas,

I'm glad that it looks like a resolution to your problem is in sight!

My second suggestion would result only in a problem marker on the 
particular Root instance that contained conflicting Class1 and Class2 
instances.  Unfortunately, it would be difficult in that case to 
actually present the user with useful error messages:  how to indicate 
*which* Class1 and Class2 instances are at fault?

My first suggestion is slightly better, because at least it puts a 
problem marker on each violating Class1 instance.  However, it doesn't 
allow a Class1 to have the same attribute value as a Class2 in some 
other Root than the one containing the Class1 in question.

Assuming you have a back-reference to the containing Root element in a 
Class1, you could do:

context Class1
inv:
    self.root.classes2->forAll(value2 <> self.value1)

Lacking the back-reference, you could do this which is actually quite 
similar to what you already had:

context Class1
inv:
    let root : Root = Root.allInstances()->any(classes1->includes(self)
    in
        root.classes2->forAll(value2 <> self.value1)

I think this gets you as close as possible, given the current EMF 
Validation / GMF Audits implementation.

cW


Achilleas wrote:
> Hi Christian,
>
> I did it as follows:
>
> context Class1:
> inv:
> Root.allInstances()->forAll(e | e.classes2->exists(c | c.value = 
> self.value))
>
> But i believe both of your ways are better!
> I thought that only for the Root class we can use the allInstances() 
> when the context (domain element target) is set to another class.
> Your 2nd example is even more expressive and resolves the problem I 
> have, where the error is depicted on all instances of the element,e.g. 
> when i impose the constraint:
>
> context Class:
> inv:
> Class.allInstances()->forAll( c1, c2 | c1 <> c2 implies c1.id <> c2.id )
>
> This produces an error that appears on all instances. I believe with 
> your 2nd constraint this is contained only to the two specific instances 
> that have the same "id"??? Anyway I will try it out to see if that's the 
> case!
>
> Thanks,
>
> Achilleas