Re: [rules-users] First Order Logic - METHODS in Drools

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be synonymous with Object and Object expressions; the only way of using methods has been via "eval" (AFAIK, as per my outdated knowledge); and this is discouraged for the fact that evals perhaps dont fit in the RETE-OO scheme of things.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