| Copying objects with eOpposite-references [message #495276] |
Wed, 04 November 2009 13:19  |
Eclipse User |
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Originally posted by: c.krause.cwi.nl
Hi,
since I haven't seen anything about it here in the newsgroup, I'm
posting about a potential issue that I found regarding copying and
comparison of eObjects. Essentially, it's the fact that
EcoreUtil.equals(o, EcoreUtil.copy(o))
does not necessarily always returns true, as one might expect. The issue
appears with features that have an eOpposite. For instance something
like this:
MyClass1 o1 = new MyClass1Impl();
MyClass2 o2 = new MyClass2Impl();
o1.setMyClass2(o2); // eOpposite reference
MyClass1 copy = (MyClass1) EcoreUtil.copy(o1);
System.out.println(EcoreUtil.equals(o1, copy)); // says "false"
I don't know whether this belongs to the general folk wisdom so I posted
it here for people that are not aware of this.
Ciao,
Christian
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| Re: Copying objects with eOpposite-references [message #495354 is a reply to message #495276] |
Wed, 04 November 2009 15:45  |
 Ed Merks
Messages: 33133
Registered: July 2009 |
Senior Member |
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Christian,
Comments below.
Christian Krause wrote:
> Hi,
>
> since I haven't seen anything about it here in the newsgroup, I'm
> posting about a potential issue that I found regarding copying and
> comparison of eObjects. Essentially, it's the fact that
>
> EcoreUtil.equals(o, EcoreUtil.copy(o))
>
> does not necessarily always returns true, as one might expect.
Yes, that' possible with bidirectional references.
> The issue appears with features that have an eOpposite. For instance
> something like this:
>
> MyClass1 o1 = new MyClass1Impl();
> MyClass2 o2 = new MyClass2Impl();
>
> o1.setMyClass2(o2); // eOpposite reference
>
> MyClass1 copy = (MyClass1) EcoreUtil.copy(o1);
> System.out.println(EcoreUtil.equals(o1, copy)); // says "false"
>
>
> I don't know whether this belongs to the general folk wisdom so I
> posted it here for people that are not aware of this.
The reason is that copying should never modify the original objects so a
bidirectional reference should never refer to an original object because
that original would point at a copy and therefore would be modified.
>
> Ciao,
> Christian
Ed Merks
Professional Support: https://www.macromodeling.com/
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