Re: [epsilon-dev] Concordance Model object creation

[Dimitris Kolovos <dimitris.kolovos@xxxxxxxxxx>]

Hi Maarten,

What will happen then if two plugins provide extensions to the extension point?

Cheers,
Dimitris

On 11 February 2014 12:26, Maarten Bezemer <maarten.bezemer@xxxxxxxxx> wrote:
> On Tuesday 11 February 2014 11:15:59 Dimitris Kolovos wrote:
>
>> To avoid confusion I'd suggest calling it an IConcoranceModel instead
>> as there's already an IModel in Epsilon
>>
> http://dev.eclipse.org/svnroot/modeling/org.eclipse.epsilon/trunk/plugins/org.eclipse.epsilon.eol.engine/src/org/eclipse/epsilon/eol/models/IModel.java
>
> I indeed noticed the other IModel interface, AFAIK there is also another Model
> class. I could also rename the concordance Model class to
> ConcordanceModelImpl.
>
>> >> Next thing is to be able (as an user of Epsilon/Concordance) to provide a
>> >> custom implementation of the Model interface.
>> >> Currently, I used an extension point to register my custom factory
>> >> (implementing a new IModelFactory interface) which creates my custom
>> >> implementation of IModel.
>> >>
>> >> This works nicely and is least intrusive I think.
>> >> By default the ModelFactory implementation is used creating the
>> >> default/current Model objects. So nothing changes for existing users.
>> >>
>> >> But, (mis)using an extension point to 'configure' the ModelFactory seems
>> >> wrong? Instead a public static method could be called to register the
>> >> factory, although this does not seem very nice as well and might result
>> >> in
>> >> the default factory being used until the call is made (which might also
>> >> be
>> >> the case using extension points...)
>>
>> One option would be to introduce a preference page that would allow
>> users to select the model factory they'd like to use (extenders would
>> still contribute model factories through the extension point).
>
> Letting the user choose the IConcordanceModel implementation does not make
> much sense:
>  * Without the correct implementation applications (might) break (applications
> must choose)
>  * Users do not care what model implementation is used, it just need to work.
>
> So, I do not think that a preference page is the way to go..?
>
> Another possibility (to circumvent extension points) would be to directly call
> a (static) method of the IConcordanceModel factory, to 'configure' the required
> model type. But personally I (slightly) like the extension point better, as
> this seems more 'natural' and less of a hack.
>
> Cheers,
>   Maarten
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-- 
Dr Dimitris Kolovos
Lecturer in Enterprise Systems
Department of Computer Science
University of York
http://www.cs.york.ac.uk/~dkolovos

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