[news.eclipse.technology.emft] Re: [EMF Compare] MergeService doesn't co

[laurent Goubet <laurent.goubet@xxxxxxx>]

Hi Stephen,

With two differences as you've described, EMF Compare will indeed need 
two steps for this child reference to be copied : you have an added 
element A with a reference towards the child C of another added element 
B. Merging only A will not copy C since B hasn't been copied yet, but 
merging B subsequently will copy C _and_ restore the link from A to C.

We've implemented the merge as such so has to only merge the differences 
the user selected, not ones that are not directly linked. MergeService 
is final as it simply isn't meant to be subclassed, but you can force 
EMF Compare to consider your two differences to be linked (and thus 
needing to be merged together) through the use of the 
org.eclipse.emf.compare.diff.extension extension point.

Laurent Goubet
Obeo

Stephen McCants a écrit :
> Resending with proper subject line.
>     --Stephen
>
> -------- Original Message --------
> Subject: MergeService doesn't copy a child non-containment reference
> Date: Thu, 30 Jul 2009 13:39:39 -0500
> From: Stephen McCants <stephenmccants@xxxxxxxxx>
> Organization: EclipseCorner
> Newsgroups: eclipse.technology.emft
>
> Hello,
>
> We have a model and are doing the match, diff and merge.  Everything is 
> working correctly, except
> the merge fails to merge in one object.
>
> The diff correctly identifies an object that has been added to the 
> model.  That added object has a
> non-containment reference to another object.  When we do the merge, it 
> correctly copies the added
> object to the left model (from the right model), but the non-containment 
> reference is never set.
> Instead of being set, it is null.
>
> We traced through the copy code and it is trying to copy it in
> EMFComapreEObjectCopier.copyReferences() by calling copyReference().  
> However, the call to
> copyReference() does nothing because we haven't copied it before (so it 
> isn't returned by get()) and
> the mergeLinkedDiff() function returns false.
>
> The reason mergeLinkedDiff() returns false is because the reference 
> being copied is a child of an
> unmatched element and not an unmatched element itself.
>
> We were going to try to override the Copier and make some adjustments to 
> work around this problem,
> but there seems to be no way to do that (MergeService is final and 
> MergeService.getCopier() always
> uses the EMFCompareEObjectCopier()).
>
> Any ideas on what we can do to get the MergeService to copy the 
> non-containment reference over?
>
> Thanks!
>
>     --Stephen

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