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Re: [eclipse-incubator-e4-dev] What I dislike about using EMF for e4...
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On Thu, Apr 17, 2008 at 11:15 AM, Michael Scharf <
Michael.Scharf@xxxxxxxxxxxxx> wrote:
[snip!]
The basic idea is that your model has no (public)
is-a relationship to a meta-model implementation,
but there is a kind of adapter that gives you
access to the meta-model. If we don't like to have
the adapter, then a getMetaModel() or getType()
method on the model would turn the is-a into a
has-a relationship.
The big advantage is that there is no is-a relationship
of the model objects (interfaces) to the underlying
implementation. So, you can change the meta-model
implementation without breaking clients. With the
meta-model as public part of the model you create
tight coupling that makes me feel uncomfortable.
Michael, I really like the idea of using an Adapter pattern to gain access to any underlying implementation details. I also think that there should be -no- EMF classes/ifaces in the modeling API (including the event notification). Using an adapter (rather than the more specific 'getImplementation' method) opens the door for some very interesting cross-model capabilities. For example model implementors (i.e. EMF) could not only support 'adapting' a ModelElement to EObject but could also support 'adapting' to a databinding 'Observable' (or JSON...).
Another example (that I might use) is to adapt a particular Model to 'IMemento' so that I can integrate it with the existing API structure (all of our save/restore code uses IMemento as the persistence API).
Eric
