Can you submit a pull request against master, 6.x, with the test. Put it in BackwardChainingTest. We'll back port the test and fix to 5.x. thanks Mark On 21 Jun 2013, at 16:00, Wolfgang Laun <wolfgang.laun(a)gmail.com&gt; wrote: > Trying to use eval in a query for backward chaining causes a runtime > crash running Drools 5.5.0. Looks like a bug. The details: > > Given some Integer objects as facts, > rule "find triple forward" > when > Integer( $a: intValue ) > Integer( $b: intValue > $a ) > Integer( $c: intValue > $b ) > eval( $a*$a + $b*$b == $c*$c ) > then > System.out.println( "fwd: " + $a + " " + $b + " " + $c ); > end > finds Pythagorean triples. > > But > query isTriple( Integer $a, Integer $b, Integer $c ) > Integer( intValue == $a ) > Integer( intValue == $b && > $a ) > Integer( intValue == $c && > $b ) > eval( $a*$a + $b*$b == $c*$c ) > end > intended to be used in combination with > rule "find triple backward" > when > isTriple( $a, $b, $c; ) > then > System.out.println( "bwd: " + $a + " " + $b + " " + $c ); > end > causes a nasty runtime error (although DRL compilation succeeds): > Exception in thread "main" java.lang.NoSuchMethodError: > pythagoras.Rule_isTriple_17ac16f7237046ee9562afce35dfe174.eval0(III)Z > at > pythagoras.Rule_isTriple_17ac16f7237046ee9562afce35dfe174Eval0InvokerGenerated.evaluate(Unknown > Source) > at > pythagoras.Rule_isTriple_17ac16f7237046ee9562afce35dfe174Eval0Invoker.evaluate(Unknown > Source) > at org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:114) > at > org.drools.reteoo.EvalConditionNode.assertLeftTuple(EvalConditionNode.java:176) > at > org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:196) > at > org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:71) > at org.drools.reteoo.JoinNode.propagateFromRight(JoinNode.java:159) > at org.drools.reteoo.JoinNode.assertObject(JoinNode.java:148) > at > org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497) > at > org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:382) > at > org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:235) > at > org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:240) > at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:350) > at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:311) > at > org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:903) > at > org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:847) > at > org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:269) > at pythagoras.Main.makeFacts(Main.java:94) > at pythagoras.Main.execute(Main.java:78) > at pythagoras.Main.main(Main.java:103) > > -W > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users