[rules-users] Better way to run each rule once?

Greetings fellow Droolers, Each of our rules modifies the fact it matches. We'd like to run each of those rules exactly once, not reactivating them when a fact changes. I see from the archives that I'm not the first person to discover that no-loop is too weak and lock-on-activate too strong for my purposes. I implemented our requirement with an AgendaListener that remembers hashes of rules + facts. This works but requires each fact to implement an interface with a method that returns the hash, and means TWO casts each time I examine a FactHandle. The whole AgendaFilter is below so you can see what I mean. Can anyone suggest a better way? I'm looking more for a better approach altogether than I am for critique of the implementation of my current approach, although the latter would not be unwelcome. private static class Once implements AgendaFilter { private final Set<Integer> alreadyActivatedRules = new HashSet<Integer>(); public boolean accept(Activation activation) { int hash = activation.getRule().getName().hashCode(); for (FactHandle handle: activation.getFactHandles()) { Object object = ((DefaultFactHandle) handle).getObject(); hash *= 31; if (object instanceof Identifiable) { hash += ((Identifiable) object).getIdentity(); } else if (object instanceof String) { // We get here when a rule uses from on a string collection hash += object.hashCode(); } else { throw new IllegalStateException( "Don't know what to do with fact class " + object.getClass() + ", value " + object); } } boolean accept = !alreadyActivatedRules.contains(hash); alreadyActivatedRules.add(hash); return accept; } } Thanks & cheers, -- | Dave Schweisguth http://schweisguth.org/~dave/ | | Home: dave at schweisguth.org Work: http://www.nileguide.com/ | | For compliance with the NJ Right to Know Act: Contents partially unknown |