Ideally you should not need to rely on no-loop behaviour, instead making your rules logically correct no matter what order they fire in etc... its a bit of a different way of thinking really.
On 1/19/06, Ephemeris Lappis <[EMAIL PROTECTED]> wrote: > > Thanks for your response. > Things seem clear for the "no-loop" and for the hand-made loop control for > other cases too. > > -- > Ephemeris Lappis > > -----Message d'origine----- > De : Michael Neale [mailto:[EMAIL PROTECTED] > Envoyé : mercredi 18 janvier 2006 23:54 > À : user@drools.codehaus.org > Objet : Re: [drools-user] [Drools][5.2.1] Loop control and best practice > > Yes no-loop is pretty basic, its idea is to stop RuleA causing it to fire > itself recursively. Of course, RuleA could cause RuleB to fire, which in > turn causes RuleA to fire (no-loop is not designed to stop that). > > To make sure things only fire once for the given facts, which I gather is > what you want, as you say you need to have your own memory in your model > of > what has fired. > Alternatively (perhaps, ideally) you do something like the "fish shop" > example does regarding free samples: > In your rule "customer-has-orders" where you add a free Gift CD, you can > add > a check to see if they already have a "gift CD" in the basket, and only > add > one if they don't. This ensures that the rule is always logically correct > no > matter when it fires. > > This has the added advantage that another rule may come along which adds a > gift CD, which means that the rule I described would still be correct > (otherwise they may end up with multiple Gift CDs, which would not be > stopped by controlling the loop behaviour). > > Does that make sense? > > On 1/18/06, Ephemeris Lappis <[EMAIL PROTECTED]> wrote: > > > > Hello. > > > > I've tried to build a first simple case with potential loops. > > > > The rules script is attached (I hope the list supports attachments ?)… > > I don't send the full project, but I can do it if needed. > > > > The test system is about customers, their placed orders, and the rules > are > > to select gifts that may be offered to customers depending on several > > conditions. Gifts are selected and placed into a virtual 'basket' that > > handles the decision process. > > > > Something like : > > > > - if a customer is 40 years old or more, we offer glasses. > > - If a customer has already placed order for more than 2500 €, we may > give > > a CD. > > - If the basket contains 2 gifts or more, we also give a bag to put > them. > > > > > >
