Minimum of Two variables in a drools Rule

Question

I want to find out the minimum of two variables in the LHS (Left Hand Side) of a drools rule. For example:

$variable1 : // Some value generation lines
$variable2 : // Some value generation lines
// This doesn't work
$minimumOfVariable1And2 : min($variable1,$variable2)

So how will the minimum be found out, is the question. Thanks.

Answer 1

One way:

when
    FactA($a : a, ...)
    FactB($b : b, ...)
    FactC(c < Math.min($a, $b), ...)
then
    ...

Another way:

when
    FactA($a : a, ...)
    FactB($b : b, ...)
then
    int c = Math.min($a, $b);
    ...

Now, when it becomes interesting is when FactA and FactB are the same type:

when
    Assignment($a : a, ...)
    Assignment(a < $a, ...)
    // $a this the minimum
then
    ...

because if 2 assignments have the same a, this rule will match twice (once for A1-A2 and once for A2-A1).