Hi, I have a question regarding pattern binding and eval(). The following rule calculates 4 different sums from a list of "Positions" and determines whether the ratio of the first 2 sums is smaller than the ratio of the latter 2 sums. The first version reads quite intuitively but it uses eval() which - as far as I gather from the docs - should be avoided whenever possible. The second version doesn't use eval() since it binds to a patten, namely the "Number" that represents the sum A1. But the relation cannot be seen as clearly as in version1. Is there another, more elegant way to write this rule which I miss? And does the use of eval() in this case come with any perfomance or other drawbacks? Thanks for your help! Harris # --------------------- rule "Test-version1"  when  Number( $sumA1: doubleValue ) from accumulate( Position( posType == "A1", $val : value ),  sum( $val ) )  Number( $sumA2: doubleValue ) from accumulate( Position( posType == "A2", $val : value ),  sum( $val ) )  Number( $sumB1: doubleValue ) from accumulate( Position( posType == "B1", $val : value ),  sum( $val ) )  Number( $sumB2: doubleValue ) from accumulate( Position( posType == "B2", $val : value ),  sum( $val ) )  eval ( ($sumA1 / $sumA2) <  ($sumB1 / $sumB2));  then  System.out.println("Ratio A smaller than ratio B !"); end # --------------------- rule "Test-version2"  when  Number( $sumA2: doubleValue ) from accumulate( Position( posType == "A2", $val : value ),  sum( $val ) )  Number( $sumB1: doubleValue ) from accumulate( Position( posType == "B1", $val : value ),  sum( $val ) )  Number( $sumB2: doubleValue ) from accumulate( Position( posType == "B2", $val : value ),  sum( $val ) )  Number( doubleValue  < (($sumB1/$sumB2)* $sumA2) ) from accumulate( Position( posType == "A1", $val : value ),  sum( $val ) )  then  System.out.println("Ratio A smaller than ratio B !"); end # --------------------- -- View this message in context: http://drools.46999.n3.nabble.com/pattern-binding-and-eval-tp3597935p3597... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users