3:30 p.m.
If you have the control fact that handles the "applied == false" condition you
wouldn't need to prevent reactivation of the rule. It would be handled by the
condition.
I'm thinking Edson's accumulate suggestion would be best, at this point.
If I understand correctly, what you want is this:
1) One rule Fact/Charge activation per Charge instance, with no reactivation when the Fact
is updated.
2) Other Fact dependent rule activations when the Fact is updated.
The problem with making (1) happen is that you'd still have the matched Fact being
updated once per Charge, which could lead to reactivation of the rules in (2) multiple
times, which you may not want. If you use accumulate in the Fact/Charge rule, plus
no-loop to prevent reactivation, you get the best of both worlds: single activation of the
Fact/Charge rule, with a single update to notify other rules that the Fact has changed.
I think what you're after is some kind of "modify group," where multiple
calls to modify are counted as just one, and rules are notified when the group is closed
out. I'm not sure how that would be implemented, because how do you know when the
modifications are finished? A low priority rule, possibly? Anyway, it doesn't exist
in drools, afaik.
You could do that kind of thing with an additional rule that tests for the nonexistence of
an unprocessed Charge, then does the update. Adding in the control fact for tracking
Charges:
rule "Update Amount"
when
amountFact : Fact(name == "Amount")
$charge : Charge()
chargeTracker : ChargeTracker(charge == $charge, applied == false)
then
Double amount = amountFact.getAmount();
Double chargeAmount = charge.getAmount();
amountFact.setAmount(amount + chargeAmount);
chargeTracker.setApplied(true);
update(charge);
end
rule "Close Facts After Charges Applied"
no-loop false
when
amountFact : Fact(name == "Amount")
not ChargeTracker(applied == false)
then
update(amountFact);
end
You'd probablt also have to prevent the "Close Facts" rule from firing when
there's just no ChargeTrackers in working memory, too.
Give that a try.
--- On Tue, 11/4/08, Dan Seaver <dan.seaver(a)ge.com> wrote:
From: Dan Seaver <dan.seaver(a)ge.com>
Subject: Re: [rules-users] Chart notation, update, and infinite loops
To: rules-users(a)lists.jboss.org
Date: Tuesday, November 4, 2008, 1:55 PM
Greg,
1) Yes, in this case I'm looking for the cartesian
join.
2) No, I can't add a property to Charge as it's
part of our corp Object
Model.
However, I could create a third object that manages whether
the Charge has
been processed which works just fine. Unless there is a
simpler strategy /
technique, I'll go with that.
Do you know of any way to keep the rule from being put back
on the agenda
when amountFact is updated? I want other rules to know that
it's been
updated, just not the rule that made the change.
Dan
Greg Barton wrote:
>
> 1) Do you want to apply all Charges in working memory
to all "Amount"
> Facts? I ask because the rule is a cartesian join
(i.e. no relation
> between matched objects) and that sometimes performs
in ways users don't
> expect. (i.e. all combinations of objects that match
the conditions are
> affected by the rule)
> 2) Can you add a property to the Charge object? Then
you could use a
> boolean named "applied" to prevent future
matches.
>
> Rule "Update Amount"
> when
> amountFact : Fact(name == "Amount")
> charge : Charge(applied == false)
> then
> Double amount = amountFact.getAmount();
> Double chargeAmount = charge.getAmount();
> amountFact.setAmount(amount + chargeAmount);
> update(amountFact);
> charge.setApplied(true);
> update(charge);
> end
>
> If a charge could be applied to multiple Facts you
could maintain an
> "appliedTo" list of Facts in the Charge, and
check that instead of a
> simple boolean.
>
> --- On Tue, 11/4/08, Dan Seaver
<dan.seaver(a)ge.com> wrote:
>
>> From: Dan Seaver <dan.seaver(a)ge.com>
>> Subject: [rules-users] Chart notation, update, and
infinite loops
>> To: rules-users(a)lists.jboss.org
>> Date: Tuesday, November 4, 2008, 11:50 AM
>> I'm trying to find a good technique for
updating
>> specific facts in working
>> memory. What I'm currently doing is something
like
>> this:
>>
>> Rule "Update Amount"
>> when
>> amountFact : Fact(name ==
"Amount")
>> charge : Charge()
>> then
>> Double amount = amountFact.getAmount();
>> Double chargeAmount = charge.getAmount();
>> amountFact.setAmount(amount + chargeAmount);
>> update(amountFact);
>> end
>>
>> The update statement causes an infinite loop.
>> I tried using no-loop, which works if there is 1
charge,
>> but not if there
>> are more than one.
>>
>> Any help with solutions or strategies would be
much
>> appreciated.
>> --
>> View this message in context:
>>
http://www.nabble.com/Chart-notation%2C-update%2C-and-infinite-loops-tp20...
>> Sent from the drools - user mailing list archive
at
>> Nabble.com.
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users(a)lists.jboss.org
>>
https://lists.jboss.org/mailman/listinfo/rules-users
>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
--
View this message in context:
http://www.nabble.com/Chart-notation%2C-update%2C-and-infinite-loops-tp20...
Sent from the drools - user mailing list archive at
Nabble.com.
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