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Syntax for use of ecore types within HUTN [message #878747]

Tue, 29 May 2012 17:21

Eclipse User

I have a minimal model expressed in EMF:
package ThingWrappers;

class ThingWrapper {
attr String name = "";
val ecore.EClassifier thing;
}

I define the attribute 'thing' on class ThingWrapper to be of type ecore.EClassifier such that it may accommodate actual things of any type within the EClassifier hierarchy. I would like to create a test model using HUTN to instantiate the model:

@Spec {
metamodel "ThingWrappers" {
nsUri: "ThingWrappers"
}
metamodel "ecore" {
nsUri: "<link to ecore metamodel>"
}
}

ThingWrappers {
ThingWrapper "TW1" {
name: "My Thing Wrapper"
thing: EBoolean#true
}
}

What's the correct syntax for assigning the Boolean value 'true' to 'thing'?

Thanks in advance ...

Re: Syntax for use of ecore types within HUTN [message #879135 is a reply to message #878747]

Wed, 30 May 2012 11:27

Eclipse User

Hi Chris,

I'm not quite clear on what you'd like to achieve, because EBoolean#true isn't an instance of EClassifier. (In fact, I'm pretty sure EBoolean#true isn't an instance of anything in Ecore: "true" is just a string that EcoreFactory recognises and uses to create a copy of java.lang.Boolean.TRUE).

Do you want to be able to reference an EClassifier (i.e. any instance of EClass or EDataType) from ThingWrapper? If so, then the following should do the trick:

@Spec {
	metamodel "ThingWrappers" {
		nsUri: "ThingWrappers"
	}
	metamodel "Ecore" {
		nsUri: "http://www.eclipse.org/emf/2002/Ecore"
	}
}

ThingWrappers {
	ThingWrapper {
		thing: EClass "Foo" {}
	}
}

If you'd like to be able to wrap any model element, then you'd need to set the type of the thing reference to be EObject. If you'd like to be able to wrap any primitive, than we may need to do some further investigation, as I'm pretty sure Ecore doesn't support this natively.

Hope this helps,
Louis.

Re: Syntax for use of ecore types within HUTN [message #879264 is a reply to message #878747]

Wed, 30 May 2012 17:50

Eclipse User

Hi Louis,
I'd like to be able to wrap instances of classes defined in my metamodel that are not necesarily related by class hierachy, and also instances of primitives such as the Boolean values, Integer values, etc. In XMF I would have set the attribute 'thing' to be of type XCore:Element.

I'd expected to be able to write something like:
@Spec {
<blah>
}

ThingWrappers {
ThingWrapper "TW1" {
name: "My Thing Wrapper"
thing: true
}
ThingWrapper "TW2" {
name: "Box Wrapper"
thing:
BoxOfChocolates "Chocs" {
name: "Milk Chocolates"
}
}
}

Best Wishes
Chris

Re: Syntax for use of ecore types within HUTN [message #880964 is a reply to message #879264]

Sun, 03 June 2012 10:03

Eclipse User

Hi Chris,

Thanks a lot for the clarification; I think that I understand now.

Unfortunately, I'm almost certain that EMF doesn't have an equivalent of the "thing" type. In fact, I think that primitive and model element types are disjoint in Ecore. One possible way to approach this would be to have a slightly less elegant metamodel, that provides separate wrappers for the primitives and for model elements:

class BooleanWrapper {
  attr Boolean[1] value;
}

class IntegerWrapper {
  attr Integer[1] value;
}

// etc, for other primitive values

class ThingWrapper {
  val EObject[1] thing;
}

With this metamodel, the HUTN would be as follows:

@Spec {
  <blah>
}

ThingWrappers {
  ThingWrapper "TW1" {
    thing: BooleanWrapper { value: true }
}
  ThingWrapper "TW2" {
    thing:  BoxOfChocolates "Chocs" {
      name: "Milk Chocolates"
   }
  }
}

I hope this (slightly clunky) solution will work for you. If not, then we should perhaps ask for some help on the EMF forum.

Cheers,
Louis.

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