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[Xtend] Accessing EClass of a model element? [message #543725]

Wed, 30 June 2010 12:26

Abdull

Messages: 32
Registered: May 2010

Member

Hello everybody,

within an Xtend transformation, is there an easy way to access a model element's EClass?

Imagine I have an .ecore file that contains EClasses A, B, C, and D.
Further imagine I have an instance of said .ecore file with model elements a1, a2, a3, b1, c1, c2.
...a1, a2, and a3 are of type A
...b1 is of type B and
...c1 and c2 are of type C.

Within an Xtend transformation I would like to identify all used EClasses. For instance, with the set myInstances = {a1, a2, a3, b1, c1, c2}, I'd like to derive a new set {A, B, C}.

Currently, I'm using the rather cumbersome way of

myInstances.collect(e|e.metaType).toSet()

then an element "aMetaType" of this derived set is processed the following way:

let typeName = aMetaType.toString() :
	switch (typeName) { 
		case 'myPackage::A' : someExpression1
		case 'myPackage::B' : someExpression2
		case 'myPackage::C' : someExpression3
		case 'myPackage::D' : someExpression4
		default : expressionForUnknownType
	};

(... e.metaType is of type xpand2::Type)
This solution depends on string equality which is not nice imho.
So, coming back to my initial question: what is the easiest and nicest way to get a model element's EClass?

Thanks, Abdull

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Re: [Xtend] Accessing EClass of a model element? [message #543731 is a reply to message #543725]

Wed, 30 June 2010 12:44

Christian Dietrich

Messages: 14670
Registered: July 2009

Senior Member

Hi, why don't you make use of a (Java) Extension?

ecore::EClass eClass(emf::EObject o) :
	JAVA template.Helper.eClass(org.eclipse.emf.ecore.EObject);

package template;

import org.eclipse.emf.ecore.EClass;
import org.eclipse.emf.ecore.EObject;

public class Helper {
	
	public static EClass eClass(EObject o) {
		return o.eClass();
	}

}

«DEFINE main FOR Model»
«FILE "test.txt"»
«this.eRootContainer.eAllContents.eClass().toSet().name»
«ENDFILE»
«ENDDEFINE»

Regards,
Christian

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

[Updated on: Wed, 30 June 2010 12:47]

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Re: [Xtend] Accessing EClass of a model element? [message #543799 is a reply to message #543731]

Wed, 30 June 2010 15:27

Abdull

Messages: 32
Registered: May 2010

Member

Great, this works - thank you Christian!

I guess I cannot use a property "myobject.getEClass()" directly (that is, I have to use your given JAVA extension), as the EMF public interface EObject exposes a method of name "eClass()", and not of name "getEClass()".

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Re: [Xtend] Accessing EClass of a model element? [message #543803 is a reply to message #543799]

Wed, 30 June 2010 15:41

Christian Dietrich

Messages: 14670
Registered: July 2009

Senior Member

Hi,

the eClass() Method is not directly available cause the Xtend EMF Metamodel Implementation does not support this. feels free to file an enhancement request to bugzilla.

Regards,
Christian

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

[Updated on: Wed, 30 June 2010 15:48]

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Re: [Xtend] Accessing EClass of a model element? [message #544654 is a reply to message #543799]

Mon, 05 July 2010 08:10

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Abdull schrieb:
> Great, this works - thank you Christian!
>
> I guess I cannot use a property "myobject.getEClass()" directly (that
> is, I have to use your given JAVA extension), as the EMF public
> interface EObject exposes a method of name "eClass()", and not of name
> "getEClass()".

You could use the JavaBeansMetamodel instead of the EMF Metamodel.
To do so change the corresponging configuration in your workflow file as
well as in the preferences of your Eclipse workbench.
The main difference is that you use the java qualified names instead of
the shorter EMF namespaces (which boils down to a different import
statement in your Xtend and Xpand files).

Using JavaBeans Metamodel is better since it integrates better with
other Java types and Java extensions. Also the tooling is slightly
better since it is based on JDT and doesn't need the long running EMF
analyzers.

Sven

--
Need professional support for Xtext and EMF?
Go to: http://xtext.itemis.com
Twitter : @svenefftinge
Blog : blog.efftinge.de

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