[aspectj-users] Aspect per object instance

["Enrique J. Amodeo Rubio" <eamodeorubio@xxxxxxxxxxxxxx>]

Hi,

I have a question about aspect instantiation, how can I have an aspect 
instance per each object of a determinated class? In this way we could 
create an aspect like the following (some sintax, like perobject are 
invented):

public abstract aspect SubjectObserverProtocol perobject(Subject+)
{
	private Set observers = new HashSet();
	public void notifyObservers(Event ev)
	{
		Iterator it=observers.iterator();
		while(it.hasNext())
		{
			update((Observer)it.next(),ev);
		}
	}

	public void addObserver(Observer o)
	{
		observers.add(o);
	}

	// follows point-cuts and advice to capture when is necesary to
	// update the subject.

	pointcut abstract updateObserver(Subject o,Event e);
	protected abstract void update(Observer o,Event ev);
	void after(Subject o,Event e) : updateObserver(o,e)
	{
		o.aspectOf().notifyObservers(e);
	}
}

It should be a concrete aspect implementing updateObserver and update 
method for each. Subject and Observer are empty interfaces. An important 
point is avoiding collisions.

Does anybody know how to do this with aspectJ? Is necesary add more 
functionality like the perobject keyword? Is there any work-around or 
idiom? I feel there should be a good way to implement this kind of 
functionality in an elegant way using aspectJ.

Thank you in advance,

	Enrique J. Amodeo Rubio