Re: [rules-users] Easy mistake...

Hi All, Just wanted to share with you an easy mistake. This is done running Drools 5.5.0.Final. Imagine a fact |Cheese (|| || creationTick : double|| || preservationTicks : double|| ||)| Then the following does not do what you expect: |rule "dump old cheese"|| || when|| || $c : Cheese( $sbd : creationTick + preservationTicks )|| || CurrentTime( tick >= $sbd )|| || then|| || System.out.println("||we have to dump "+$c);|| ||end| You would expect that $c is dumped when current time has passed creationTick + preservationTicks. But no. The variable $sbd is bound to creationTick /before/ the preservationTicks are added!! I must say that I do not quite understand how ($sbd : creationTick) + preservationTicks resolves to "true" to make the premise succeed... Maybe because it is != 0? I found that it should be: |rule "dump old cheese"|| || when|| || $c : Cheese( $sbd : (creationTick + preservationTicks) )|| || CurrentTime( tick >= $sbd )|| || then|| || System.out.println("we have to dump "+$c);|| ||end| This makes sense. Now $sbd is bound to the result of the addition. But it is an easy trap!! Regards, Willem