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

[Dan Seaver]

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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>>
> 
> 
> 
> -- 
>  Edson Tirelli
>  JBoss Drools Core Development
>  JBoss, a division of Red Hat @ www.jboss.com
> 
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> 
> 

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