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Ecore/EVL check component is instantiated [message #1847601]

Tue, 02 November 2021 09:10

Gary Collins

Messages: 5
Registered: November 2021

Junior Member

I'm new to Eclipse Epsilon.
I created a meta model in Ecore and have written some EVL constraints.
But unable to write EVL constraint that checks if a component is instantiated.

* Created Ecore model with various components
* Between 2 components (component A and B) created a Composition Relation [1..1]
* Created dynamic instance (.xmi file)

I want to check if component B is instantiated in EVL.

If I validate the model it shows (as expected) that component B is not yet created with message ("The required feature 'containsFoo' of ''Model myModel must be set").

But how to do the same in EVL constraint ?

Tried checking the ref of component A but it will pass even without a component B.

	// check component has references 
	constraint HasReferenceToFoo {
		check: self.eClass().getEReferences().exists(c | c.name == "containsFoo")
		message: "Missing a reference to Foo" 
	}

Any help will be much appreciated.

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Re: Ecore/EVL check component is instantiated [message #1847604 is a reply to message #1847601]

Tue, 02 November 2021 09:42

Dimitris Kolovos

Messages: 2165
Registered: July 2009
Location: York, UK

Senior Member

Hi Gary,

The following should do the trick.

context A {
  constraint ContainsFoo {
    check: self.containsFoo.isDefined()
  }
}

Best,
Dimitris

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Re: Ecore/EVL check component is instantiated [message #1847606 is a reply to message #1847604]

Tue, 02 November 2021 10:07

Gary Collins

Messages: 5
Registered: November 2021

Junior Member

Hi Dimitris,

That worked out of the box.

Thanks !

Besides this forum what is the best place to find example EOL and EVL code ?

I'd like to view all the operations on an component/object ('self' for example).

I assume the JavaDoc is good starting point ?
https://javadoc.io/doc/org.eclipse.epsilon

I'm also reading your book (EpsilonBook) and looking at Youtube videos.

Gary

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Re: Ecore/EVL check component is instantiated [message #1847611 is a reply to message #1847606]

Tue, 02 November 2021 12:11

Dimitris Kolovos

Messages: 2165
Registered: July 2009
Location: York, UK

Senior Member

Hi Gary,

The book is no longer updated so my recommendation would be to consult the documentation pages for EVL [1] (and its base EOL [2] language) instead. The full JavaDoc is available in [3], [4] provides additional information for working with EMF models and there are also some live examples in [5]. There's a fair amount of EOL code on GitHub too [6].

Best,
Dimitris

[1] https://www.eclipse.org/epsilon/doc/evl/
[2] https://www.eclipse.org/epsilon/doc/eol/
[3] https://download.eclipse.org/epsilon/stable-javadoc/
[4] https://www.eclipse.org/epsilon/doc/articles/epsilon-emf/
[5] https://www.eclipse.org/epsilon/live/
[6] https://github.com/search?q=extension%3Aeol+var

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Re: Ecore/EVL check component is instantiated [message #1847612 is a reply to message #1847611]

Tue, 02 November 2021 12:31

Gary Collins

Messages: 5
Registered: November 2021

Junior Member

Great thanks Dimitris !

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Re: Ecore/EVL check component is instantiated [message #1847629 is a reply to message #1847604]

Tue, 02 November 2021 14:42

Gary Collins

Messages: 5
Registered: November 2021

Junior Member

Hi Dimitris,

Should the same code work in case of Composition Relation [1..*] ?

check: self.containsFoo.isDefined()

I'm tried the [1..*] with no instantiated B component but EVL passes.

Any ideas why [1..1] fails but [1..*] passes ?

Rgds,

Gary

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Re: Ecore/EVL check component is instantiated [message #1847631 is a reply to message #1847629]

Tue, 02 November 2021 14:45

Dimitris Kolovos

Messages: 2165
Registered: July 2009
Location: York, UK

Senior Member

Hi Gary,

If containsFoo is multi-valued then self.containedFoo returns a collection (and hence is always non-null). What you're looking for in this case is