our Soldier $x;

multi sub trythisone (General $y)
 {
 # $y is a read-only alias of the caller's variable, global $x in this case.
 # This function chosen based on actual type of $x at the time the call was made.
 $x = Private.new;
 # what just happened to $y?
 $y.order_attack();
 }

$x = General.new;
trythisone ($x);