Apologies if this has been addressed elsewhere: I couldn't find anything quite like my issue. My (greatly simplified and completely made-up) example: Let's say I have this java class: public class BaseballPitcher { public String getName(); public boolean isRightHanded(); public boolean isKnuckleBaller(); } Multiple instances of this class are created with a variety of combinations for the name and two boolean parameters. Now I have a rule: rule "Match pitchers: righties or knuckle-ballers" when $kbPitcher1 : BaseballPitcher($name: name, $righty: rightHanded == true || $knuckleballer: knuckleBaller == true) $kbPitcher2: BaseballPitcher(name != $name, rightHanded == $righty, knuckleBaller == $knuckleballer) then // Do something with these two pitchers $kbPitcher1 and $kbPitcher2 end I am getting the curious result that this rule fires its conclusion when $kbPitcher1 is in fact NEITHER right-handed nor a knuckle-baller (i.e. rightHanded == false && knuckleBaller == false). I've worked around this by changing the first condition in either of the following two ways: *// eval() the condition* $kbPitcher1 : BaseballPitcher($name: name, $righty: rightHanded, $knuckleballer: knuckleBaller, *eval(isRightHanded() == true || isKnuckleBaller() == true)*) ...or.... *// bind the variables before checking values* $kbPitcher1 : BaseballPitcher($name: name, $righty: rightHanded, $knuckleballer: knuckleBaller, *rightHanded == true || knuckleBaller == true*) Does this make sense? Both are easy workarounds, and I believe the second option (i.e. the one NOT using the eval) is the better solution from a performance perspective, allowing the engine to index the these facts rather than dynamically evaluate the condition every time. But I'm a little surprised the first approach didn't work. Any ideas why not? -- View this message in context: http://drools.46999.n3.nabble.com/Unexpected-variable-binding-behavior-an... 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