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Retrieving EEnumLiteral attributes [message #1861121]

Thu, 21 September 2023 15:06

Alain Picard

Messages: 266
Registered: July 2009

Senior Member

I am looking at finding out the syntax to get one of the 3 attributes from an EEnum: name, literal and value.

In my current use case I need to retrieve the value integer to use for sorting elements.

I have no problem getting the enum itself: irel.depth which is of type: core::IndirectRelationshipDepth but I can't do: irel.depth.value or irel.depth.getValue() or ???

Thanks
Alain

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Re: Retrieving EEnumLiteral attributes [message #1861122 is a reply to message #1861121]

Thu, 21 September 2023 17:13

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

The simple answer is that you cannot because, in UML, an EnumerationLiteral is just a distinctively named element of an Enumeration. There are no literal or value aspects in UML. OCL is aligned with UML so OCL too has no literal or value aspects.

However, the Pivot OCL supports Ecore and reflection so it should be possible to use oclType() to make progress. Unfortunately, an EnumerationLiteral is a very deficient object so not much works reflectively.

You can get a form of literal value via e.g.

self.color.oclType().ownedLiterals->indexOf(self.color)

(This form of reflection is not supported by OMG OCL except that the exposition of flatten() in 11.7.2 requires it. Once supported, the spelling of e.g. ownedLiterals is open to design/dispute. The Pivot OCL tries to be a bit more rational than UML.)

https://bugs.eclipse.org/bugs/show_bug.cgi?id=582449 suggests that an EnumerationLiteral could conform to a new OclEnumerationLiteral type with literal/value properties.

Workaround: you can write a Java helper in some utilty class, but beware. An EEnumLiteral has multiple Ecore representations, one of which is 'too' lightweight forcing the Pivot OCL to cache the results of a total metamodel search to map lightweight to richer representations.

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Re: Retrieving EEnumLiteral attributes [message #1861135 is a reply to message #1861122]

Fri, 22 September 2023 09:59

Alain Picard

Messages: 266
Registered: July 2009

Senior Member

Thanks Ed for the very informative reply, even if there is no obvious solution at the moment. As a workaround, since I had a single EClass using this enumeration, I added a transient, derived attribute to get the value for now. Other cases might have made this approach much more awkward, but at least for now the value is available.

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