Re: [rules-users] Roll Back Rule / Rule Transactions?

Anytime you modify a object, candidate rules are going to be re-examined. You may need some state variables in addition to this (to control when rules fire, avoid loops, etc), but the basic rules could be: rule AddVcr when $c: Cart(contents contains "TV", contents excludes "free VCR") then $c.add("free VCR"); modify($c); end rule RemoveVcr when $c: Cart(contents excludes "TV") then $c.remove("free VCR"); modify($c); end You can fill in the rest. Like I said, you probably need some state variables so things don't loop, need to exclude the case where a non-free VCR is legitimately in the cart, etc. But your basic question should be answered with this approach. Don't think procedurally, think in terms of a living system when the changes in objects trigger somewhat asynchronous cascades of matching rules. Calling modify() on a fact is like restarting the whole matching algorithm for any rules that had that fact included in their (possible candidate) constraints. On 2/13/07, Matt Johnston <MJohnston(a)pubgroup.com&gt; wrote: