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Is "Feature id" = Properties tab "ID" [message #1643439]

Sun, 01 March 2015 10:21

Eclipse User

I did look in the EMF FAQ and did a search the EMF Forum and re-read the sections 10.7.1 and 16.3 and it is still not clear to me.

EMF newbie here. In the book Eclipse EMF book second edition section 10.7.1 page 278 and section 16.3 page 521 there is a reference to use a "Feature Id"

Question 1) Is the "Feature Id" the book speaks about the same "ID" as on the properties tab in the attached screen capture?

index.php/fa/21025/0/

If the answer to question 1 is True, why is the default false"? The book highly recommends the use of the Feature Id. In other words, when would one not want to use the "Feature Id/ID"?

The focus description of "Whether the value of this attribute uniquely identifies an object within its containing resource" does not clear up the issue for me.

Attachment: Feature id.jpg
(Size: 36.28KB, Downloaded 944 times)

Re: Is "Feature id" = Properties tab "ID" [message #1643597 is a reply to message #1643439]

Sun, 01 March 2015 12:14

Eclipse User

Hi

The two concepts are completely different.

The EAttribute::iD attribute is similar to the UML/MOF Property::isID
which is a Boolean that indicates whether the attributed EAttribute can
provide an identifier for its containing class. This maybe exploited by
XMI serialization.

EStructuralFeature::getFeatureID() provides a distinct Integer index for
the EStructuralFeature in the eAllStructuralFeatures of the containing
EClass. Make sure you understand the derivedFeatureID subtleties before
using this for non-trivial classes.

Regards

Ed Willink

On 01/03/2015 15:21, Paul Roubekas wrote:
> I did look in the EMF FAQ and did a search the EMF Forum and re-read the sections 10.7.1 and 16.3 and it is still not clear to me.
>
> EMF newbie here. In the book Eclipse EMF book second edition section 10.7.1 page 278 and section 16.3 page 521 there is a reference to use a "Feature Id"
>
> Question 1) Is the "Feature Id" the book speaks about the same "ID" as on the properties tab in the attached screen capture?
>
>
>
> If the answer to question 1 is True, why is the default false"? The book highly recommends the use of the Feature Id. In other words, when would one not want to use the "Feature Id/ID"?
>
> The focus description of "Whether the value of this attribute uniquely identifies an object within its containing resource" does not clear up the issue for me.

Re: Is "Feature id" = Properties tab "ID" [message #1643680 is a reply to message #1643597]

Sun, 01 March 2015 13:09

Eclipse User

Thanks for the quick answer. Hope to return the favor some day.

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