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Differences in URI values [message #1751843]

Mon, 16 January 2017 02:39

Eclipse User

I want to get the URI of my data.
So, I have this object called x.

I noticed that I can get the URI in different ways.
[1] x.eContainingFeature.eContainer.eResource.URI
[2] x.eResource.URI
[3] x.eContainer.eResource.URI

What are the differences of these 3 URI values? Should I expect them to always contain the same values?

[Updated on: Mon, 16 January 2017 02:40] by Moderator

Re: Differences in URI values [message #1751844 is a reply to message #1751843]

Mon, 16 January 2017 02:52

Eclipse User

no

(2) and (3) should give you the same result,
but (1) navigates from the model to the metamodel and thus will give you the metamodels resource

Re: Differences in URI values [message #1751846 is a reply to message #1751844]

Mon, 16 January 2017 03:01

Eclipse User

sorry, i am not very familiar with the terminology.
what is the difference between model and metamodel?
what are the instances where the URI in model differs from the one in metamodel?

Re: Differences in URI values [message #1751847 is a reply to message #1751846]

Mon, 16 January 2017 03:06

Eclipse User

an easy analogy would be the terms classes and objects/instances

in emf lets say there is a class Person that has/owns an Adress what has an Attribute name
you have a Person "Hugo" that lives at "AStreet".

having the "AStreet" in hand "eContainer" will gives you "Hugo"
but eContainingFeature will give you "Field adress of Type Adress of Class Person"

i recommend some basic reading on EMF

Re: Differences in URI values [message #1751848 is a reply to message #1751847]

Mon, 16 January 2017 03:39

Eclipse User

Ok, thanks for the info.

Is there a way to set the eResource details? I found eSet() that will set the eContainingFeature. How to set the eResource variable?

Re: Differences in URI values [message #1751849 is a reply to message #1751848]

Mon, 16 January 2017 04:00

Eclipse User

you do it by added the root eobject to the resource.
but that should happend automatically.

can you elaborate on what you are doing?

Re: Differences in URI values [message #1751851 is a reply to message #1751849]

Mon, 16 January 2017 04:16

Eclipse User

I have two different but similar grammars.

Kids
-> name
-> address

Child
-> name
-> address

Kids is the old grammar. Then, I have to support the Child grammar. However, I have to treat both Kids and Child classes as one.
Thus, during transform, I add all the Child objects into the Kids object.
During generation and validation, I have to know the file and line number where each entry is configured.
So, I have this code:

for(m: rs.allContents.toIterable.filter(typeof(Child))) //rs is a ResourceSet
		{
			val x = MyDslFactory::eINSTANCE.createKids
			x.name = m.name
			x.address = m.address
			x.eSet(x.eContainingFeature, m.eContainingFeature)
			aKidsList.add(x)
		}

I haven't found any way to set the resource so I can retrieve the URI information later. How to do it?

Re: Differences in URI values [message #1751854 is a reply to message #1751851]

Mon, 16 January 2017 04:59

Eclipse User

which uri information? the one of m or the one of aKidsLists owner?

Re: Differences in URI values [message #1751859 is a reply to message #1751854]

Mon, 16 January 2017 05:29

Eclipse User

I want to copy the URI information of m to x.

Re: Differences in URI values [message #1751861 is a reply to message #1751859]

Mon, 16 January 2017 05:30

Eclipse User

then you have to create a string placeholder for that

Re: Differences in URI values [message #1751862 is a reply to message #1751861]

Mon, 16 January 2017 05:32

Eclipse User

our you create a source cross reference for that

MyObject: ..... sourceEObject=[ecore::EObject|EObject] ...

Re: Differences in URI values [message #1751867 is a reply to message #1751862]

Mon, 16 January 2017 05:46

Eclipse User

It's still unclear what you are trying to do but, you can create and attach EAdapters to EObject if you want to attach additional information.

Re: Differences in URI values [message #1752025 is a reply to message #1751867]

Tue, 17 January 2017 22:02

Eclipse User

Thanks for the info. In the end, I decided to change the grammar as it is simpler to implement.

I noticed that the containing feature is also in the container itself.
Thus, is it safe to assume that for an object x:
x.eContainingFeature is always equal to x.eContainer.eContainingFeature?

Re: Differences in URI values [message #1752029 is a reply to message #1752025]

Tue, 17 January 2017 22:45

Eclipse User

No, this isn't a safe general assumption. The first is the feature of the container of x that actually contains x, i.e., you could call x.eContainer.eGet(x.eContainingFeature) and expect to find x in the result. The second is the feature that contains the container of x. They might be the same feature, but generally not because generally the container will have a completely different set of features because it's a completely different class of object.

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