[rules-users] Chart notation, update, and infinite loops

[Dan Seaver]

Unfortunately, we can't use the results of the update in the "when" clause of
other rules if we put it in a global.


Greg Barton wrote:
> 
> Put it in a global variable?
> 
> --- On Tue, 11/4/08, Dan Seaver <dan.seaver at ge.com> wrote:
> 
>> From: Dan Seaver <dan.seaver at ge.com>
>> Subject: Re: [rules-users] Chart notation, update, and infinite loops
>> To: rules-users at lists.jboss.org
>> Date: Tuesday, November 4, 2008, 2:08 PM
>> Thanks Edson,
>> I'm aware of "accumulate" and see how it can
>> be used to solve the specific
>> issue. 
>> 
>> I'm looking for a more generic solution for updating
>> objects.
>> 
>> The only reason amountFact is part of the "when"
>> clause is for a reference
>> to the object that can be used by the "then"
>> clause. It's not really part of
>> the rule criteria.
>> 
>> If I could get a reference to it directly in the
>> "then" clause, the update
>> statement would not put the rule back on the agenda - which
>> would be
>> perfect. 
>> 
>> Any ideas?
>> 
>> Dan
>> 
>> Edson Tirelli-3 wrote:
>> > 
>> >    There are several ways of doing that, and some
>> where even mentioned by
>> > the other users. One easy way is to simply use
>> "accumulate":
>> > 
>> > rule "update amount"
>> >     no-loop
>> > when
>> >     $f : Fact( name == "amount" )
>> >     Number( $total : doubleValue ) from accumulate(
>> >               Charge( $amt : amount ),
>> >               sum( $amt ) )
>> > then
>> >     modify( $f ) { setAmount( $total ) }
>> > end
>> > 
>> >     []s
>> >     Edson
>> > 
>> > 2008/11/4 Dan Seaver <dan.seaver at ge.com>
>> > 
>> >>
>> >> 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-tp20327483p20327483.html
>> >> Sent from the drools - user mailing list archive
>> at Nabble.com.
>> >>
>> >> _______________________________________________
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>> >> rules-users at lists.jboss.org
>> >>
>> https://lists.jboss.org/mailman/listinfo/rules-users
>> >>
>> > 
>> > 
>> > 
>> > -- 
>> >  Edson Tirelli
>> >  JBoss Drools Core Development
>> >  JBoss, a division of Red Hat @ www.jboss.com
>> > 
>> > _______________________________________________
>> > rules-users mailing list
>> > rules-users at lists.jboss.org
>> > https://lists.jboss.org/mailman/listinfo/rules-users
>> > 
>> > 
>> 
>> -- 
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>> Sent from the drools - user mailing list archive at
>> Nabble.com.
>> 
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> 
> 
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