[rules-users] unexpected/spurious ClassCastException

[Borris]

I am getting an unexpected cast exception. The backtrace looks like

Exception in thread "main" java.lang.ClassCastException: 
com.tastiereasier.rulez.ContextFoodItem cannot be cast to 
com.tastiereasier.domain.FoodItem
     at 
ConditionEvaluatorb792d1e4169f4ac98945e49e1412d793.evaluate(Unknown Source)
     at 
org.drools.core.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:216)
     at 
org.drools.core.rule.constraint.MvelConstraint.isAllowedCachedLeft(MvelConstraint.java:185)
     at 
org.drools.core.common.SingleNonIndexSkipBetaConstraints.isAllowedCachedLeft(SingleNonIndexSkipBetaConstraints.java:141)
     at 
org.drools.core.phreak.PhreakJoinNode.doLeftInserts(PhreakJoinNode.java:98)
     at org.drools.core.phreak.PhreakJoinNode.doNode(PhreakJoinNode.java:60)
     at 
org.drools.core.phreak.RuleNetworkEvaluator.switchOnDoBetaNode(RuleNetworkEvaluator.java:547)
     at 
org.drools.core.phreak.RuleNetworkEvaluator.evalBetaNode(RuleNetworkEvaluator.java:533)
     at 
org.drools.core.phreak.RuleNetworkEvaluator.innerEval(RuleNetworkEvaluator.java:334)
     at 
org.drools.core.phreak.RuleNetworkEvaluator.evalStackEntry(RuleNetworkEvaluator.java:224)
     at 
org.drools.core.phreak.RuleNetworkEvaluator.outerEval(RuleNetworkEvaluator.java:166)
     at 
org.drools.core.phreak.RuleNetworkEvaluator.evaluateNetwork(RuleNetworkEvaluator.java:116)
     at 
org.drools.core.phreak.RuleExecutor.reEvaluateNetwork(RuleExecutor.java:193)
     at 
org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:68)
     at 
org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:928)
     at 
org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1193)
     at 
org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1202)
     at 
org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1175)
     at com.tastiereasier.rulez.Rulez.insertAndFire(Rulez.java:168)
     at com.tastiereasier.rulez.Rulez.addDinerToContext(Rulez.java:310)
     at com.tastiereasier.rulez.Rulez.<init>(Rulez.java:101)
     at com.tastiereasier.rulez.Rulez.main(Rulez.java:44)

The rules that are triggering this are:

rule contextDinerDislike
     enabled true
     when
         ContextDiner( $diner; )
         DatumPreference
         (
             datumPreferenceType == DatumPreference.Type.PREFERENCE,
             belief.factor < 0.0,
             $datum: datum
         )
         from $diner.getDatumPreferences()
     then
         insert( new ContextFoodItem( (FoodItem) $datum, true ) );
end

rule spotNewContextDinerLike
     enabled true
     when
         ContextDiner( $diner; )
         DatumPreference
         (
             datumPreferenceType == DatumPreference.Type.PREFERENCE,
             belief.factor > 0.0,
             $datum: datum
         )
         from $diner.getDatumPreferences()
     then
         insert( new ContextFoodItem( (FoodItem) $datum, false ) );
end

If I disable either rule, then the other proceeds fine and no cast 
exception happens.

I can't see why the cast should ever be asked for - it doesn't make sense.

If I changed the boolean parameter in the new in the insert - so both 
are either true or both
are either false, there are no cast exceptions (there must be a clue here).

If I put a debug after the insertion, the backtrace actually happens 
after return from the
insert() method - implying it's something on the agenda?

I tried using the Audit stuff to see if it gave any clues - but I've 
never used that before
and simply got a heap exhaustion from Eclipse after 1/2 hour trying to 
ingest something like 200
meg of trace data - I've got a lot of data being initialised into the 
workspace before these rules
get a chance to do anything.

It's feeling remarkably like a bug to me, but I don't know how to 
interpret the backtrace usefully,
so it's possible I've got something messed up elsewhere - although I've 
disabled massive amounts
of rules that I can.

I grabbed a snapshot last night and it didn't change anything. (I was on 
a snapshot from early June to fix being able to have Drools editor 
reference my external jars.)

Does this look like a bug or user error? It's going to take some effort 
to try and extract a test case
so I really don't want to spend the effort on that unless it looks the 
only way.

Sage observations most appreciated.

Borris