Re: [cme-dev] Visiting Concerns

[Peri Tarr <tarr@xxxxxxxxxx>]

Hi Philip,

Yes, you're looking for something called
the unloader infrastructure, which--you guessed it--hasn't been implemented
yet :-).  I've been contemplating it as a project over Christmas,
though no promises there (catching up on sleep is also sounding kind of
appealing as a project :-)).

In the meantime, you're stuck with a
structure fairly similar to what you have.  Do note, however, that
you can do the instanceof tests on the interfaces, rather than the implementation
classes, which at least makes this less horrible.

Thanks for your message--you're the
first person to turn up the need for it outside of our group, so I appreciate
the extra motivation to get this capability in.  We'll keep you posted
on it.

     Peri

Philip Quitslund <pq@xxxxxxxxxx>
Sent by: cme-dev-admin@xxxxxxxxxxx

12/13/2004 05:48 PM

Please respond to
cme-dev

To	cme-dev@xxxxxxxxxxx
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Subject	[cme-dev] Visiting Concerns

Hi all.

Forgive me if this is obvious (and it probably is!) but I'm puzzling over
how to 
best traverse the structure of Concerns.  What I'm driving at is a
way to take a 
  Concern and build my own abstract representation.  I was expecting
some kind 
of visitor scheme but haven't found anything...

As a simple example, suppose I wanted to collect all the AdviceArtifacts
in a 
Concern.  I'd like to avoid code that looks like this:

                
/* final */ Collection adviceCollector = new ArrayList();

                
ConcernModelElement cme =
                
                 /*
ProxyConcernModelElement */ pcme.getConcernModelElement();
                
if (cme instanceof ConcernImpl) {
                
                 ConcernImpl
concern = (ConcernImpl)cme;
                
                 QueryableRead
elems = concern.getElements();
                
                 for
(Iterator iter = elems.iterator(); iter.hasNext();) {
                
                 
               
Object o = iter.next();
                
                 
               
if (o instanceof AdviceUnit) {
                
                 
               
                 adviceCollector.add(((AdviceArtifact)o).
                
                 
               
                 
               
getAdviceArtifacts());
                
                 
               
}
                
                 
               
...
                
                 }
                
                 ...
                
}

preferring something more like this:

cme.accept(new ConcernVisitor() {
                
                 void
visit(AdviceUnit advice) {
                
                 
               
adviceCollector.add(advice.getAdviceArtifact());
                
                 };
                
);

(Admittedly this is an overly simple example, but you get the idea.)

What's the best way to programmatically explore the structure of Concerns?

Any help would be greatly appreciated.  Thanks!



-phil





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