Re: [aspectj-users] Aspect per object instance

[Lesiecki Nicholas <ndlesiecki@xxxxxxxxx>]

Wes was right to point you at Jan Hanneman's implementation, which solves
this problem rather elegantly.

You can find information on the Design Patterns project at:

http://www.cs.ubc.ca/~jan/AODPs/

Also, my forthcoming book Matering AspectJ
(http://www.amazon.com/exec/obidos/tg/detail/-/0471431044/)
contains a full writeup on this particular pattern, including a sample
application to the problem of cache invalidation.

Cheers,

Nick

--- "Enrique J. Amodeo Rubio" <eamodeorubio@xxxxxxxxxxxxxx> wrote:
> 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
> 
> _______________________________________________
> aspectj-users mailing list
> aspectj-users@xxxxxxxxxxx
> http://dev.eclipse.org/mailman/listinfo/aspectj-users


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