[rules-users] infinite loops with "no-loop true"

[Wolfgang Laun]

Hello James,
the rule attribute lock-on-active might be what you are looking for.
-W

2009/9/23 Nord, James <JNord at nds.com>

>  Hi all,
>
> It seems to me that the no-loop only prevents a rule from triggering itself
> - and doesn't make the rule only fire once (which is what I'm after)
>
> e.g. consider the following two contrived simple rules:
>
>
> rule "addPriorityPrefix"
>  dialect "java"
>  no-loop true
>  when
>   $work : Work (priority >= 200)
>  then
>   modify($work) {
>    setTitle("!!! " + getTitle());
>   };
> end
>
> rule "re-assign low priority tasks"
>  dialect "java"
>  no-loop true
>  when
>   $work : Work (priority < -200)
>  then
>   modify($work) {
>    setOwner("nobody");
>   };
> end
>
>
> What I end up with is an infinte loop.
>
> Whilst for the simple case I can re-write them like
>     $work : Work (priority >= 200, !title.startWith("!!!"))
> however with the more complex rules this makes the rules get very complex
> quickly and less easy to write. Is there a way to prevent these loops - have
> I misunderstood or do you really need to check everything in the rule that
> you may set?
>
> How would you do the banking interest example?
>
> rule "interest calculation"
>   no-loop
>   when
>     $account : Account( )
>   then
>     modify($account) {
>       setBalance((long)($account.getBalance() * 1.01) )
>     };
> end
>
>
> if there was another rule that if you where a gold customer and payed in >
> $500 the previous month then you get $4 bonus?
>
> rule "gold bonus"
>   no-loop
>   when
>     $account : Account(type="gold", previousMonthDeposit > 500 )
>   then
>     modify($account) {
>       setBalance((long)($account.getBalance() + 4) )
>     };
> end
>
>
> Regards,
>
>     /James
>
>
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