[rules-users] drools arithmetics without eval()

[Wolfgang Laun]

accumulate is not the way to go.

If you need accumlated counts for certain facts, by type or, within
some type, by attribute value, then you should set up secondary facts
and maintain these during the element insertion process or by separate
(static) rules.

class ProductCounter {
    String id;
    int      count; }

rule count
when
    $pp: PortfolioProduct($pid: productId, prodCounted == false )
    $pc: ProductCounter( id == $pid )
then
    modify( $pc ){ setCount( $pc.getCount() + 1 ) }
end

And now you can generate the rules accessing the completed counts.
-W





On 14/03/2012, fx242 <drools at fx242.com> wrote:
> Hi,
>
> These rules are all auto-generated every day, and I don't control what is
> going into them, so this kind of optimizations won't work for me. The basic
> problem here, is that I have tons of rules that count facts
> (PortfolioProducts) and use the result as rule conditions.
> Some conditions could look like this: count(PortfolioProduct(A)) +
> count(PortfolioProduct(B)) <= ( count(PortfolioProduct(C)) -
> count(PortfolioProduct(D)) ) - count(PortfolioProduct(E))
> and so on...
>
> All rules look like the rule I've posted: I first calculate all relevant
> fact counts to be used by the rule (accumulates), and then perform the
> logic/arithmetic evaluation using evals(). Some rules end up having 15
> accumulates and 2 evals as conditions...
> My question is if using accumulate and eval() is the only choice I have to
> write these kind of rules.
>
> Regards,
> Tiago Lopes
>
> --
> View this message in context:
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> Sent from the Drools: User forum mailing list archive at Nabble.com.
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