From what I understand the problem with methods is drools has to assume that the method always returns the same result given the same set of inputs and has no side effects as it is non-deterministic how many (or few) times the method is called and if the return value changes on different calls then it can really screw things up. When writing beans getters normally follow this rule by convention and necessity, however this is much less likely for arbitrary methods hence why it is good (IMHO) to force the user to consider what they are doing explicitly.

-----Original Message----- From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users- bounces(a)lists.jboss.org] On Behalf Of Arjun Dhar Sent: 20 April 2011 05:29 To: rules-users(a)lists.jboss.org Subject: [rules-users] First Order Logic - METHODS in Drools According to First order Logic, (from a rule perspective), one can represent their statements using: PREDICATES, METHODS, CONNECTORS (including existential quantifiers) ..while PREDICATES can be synonymous with Object and Object expressions; the only way of using methods has been via "eval" (AFAIK, as per my outdated knowledge); and this is discouraged for the fact that evals perhaps dont fit in the RETE-OO scheme of things. Please note: By methods I dont bean Bean getter/setters; but work horse service layer methods. ..however, to be true to FOL, using methods directly should be supported. Q1) If it is, can one show or state an example? Q2) If not, for METHODS that return a specific type of Object, cant they be useful in RETE-OO evaluation? Q3) I've used "from" for DAO's , conceptually does "from" address this fully? In FOL (imo) PREDICATES & METHODS can be exchanged freely, not sure if "from" gives that freedom. thanks -- View this message in context: http://drools.46999.n3.nabble.com/First- Order-Logic-METHODS-in-Drools-tp2841531p2841531.html 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

I believe eval() solves that purpose functionally but is not optimal; not sure how evals() tie in with Rete-OO Specially since the return type of eval() is not known, I can seriously doubt it being optimal as using Objects directly in conditions. ----- Software documentation is like sex: If its good its really really good, if not then its still better than nothing! -- View this message in context: http://drools.46999.n3.nabble.com/First-Order-Logic-METHODS-in-Drools-tp2... 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

The reason why i started this thread was to ensure in the process of Rule engineering, I could write optimal rules in mathematical notion and not have to worry about technical differences in how a Predicate is translated while translation to drools. (ideally)

thanks everyone. ----- Software documentation is like sex: If its good its really really good, if not then its still better than nothing! -- View this message in context: http://drools.46999.n3.nabble.com/First-Order-Logic-METHODS-in-Drools-tp2... 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