[news.eclipse.tools.emf] Re: The definitive truth about multiple inherit

[Ed Merks <Ed.Merks@xxxxxxxxx>]

Guillaume,

Comments below.

Guillaume Vauvert wrote:
> Happy to join the team of EMF's users !
Welcome. :-)
> After many searches, I have found no clear answer to my basic question 
> about multiple inheritance.
>
> The EMF documentation 
> (http://help.eclipse.org/ganymede/index.jsp?topic=/org.eclipse.emf.doc/references/overview/EMF.html 
> , chapter "EMF developper guide", section "EMF developper guide", 
> subsection "EMF Framework Programmer's Guide") saids :
>
> "As in Java itself, multiple interface inheritance is supported, but 
> each EMF class can only extend one implementation base class. 
> Therefore, when we have a model with multiple inheritance, we need to 
> identify which of the multiple bases should be used as the 
> implementation base class. The others will then be simply treated as 
> mixin interfaces, with their implementations generated into the 
> derived implementation class."
>
> The example shows a model with a class [SchoolBook] that inherits 
> <<extends>> [Book] and that inherits [Asset]; this class should be 
> implemented by extending (Java) the class Book and implenting the 
> methods of the class Asset by copying them from Asset.
>
> I tried to apply that to my model :
> D inherits from A that inherits from Action, and C that inherits from 
> Class.
> The implementation of class D does provide implementations for methods 
> found in A and C, but does provide no implementations for methods 
> coming from inheritance of the class not extended (Action or Class 
> depending on the class (C or A) that D extends).
I keep reading this and it's making my brain hurt.  Maybe you could draw 
a picture or make explicit what methods you're talking about.  Is D 
inheriting from C or is it A that's doing that, or is the comma implying 
that C inherits from Class but is otherwise unrelated?
> Have I missed something ?
So far it's probably me that's missed something.
> If not, why isn't it possible for EMF to automatically generate the 
> "good" implementation ?
The point that is that if you consider the super types Y and Z of an 
EClass X, XImpl will extend YImpl and will generate a clone of what's in 
ZImpl.  So it should indeed be possible to generate a complete 
implementation.
> What can I do to solve my problem ?
Are you saying that's generated doesn't compile? 
> Thank you very much for clarify my knowledge ...
>
> Guillaume Vauvert
> http://www.ixmas.org