[cme-dev] Visiting Concerns

[Philip Quitslund <pq@xxxxxxxxxx>]

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