[rules-users] Inheritance-Like Design Question

[Edson Tirelli]

   To add constraints to a fact matched by the parent rule, use "from" :

rule "parent"
when
   $var : MyFact( ... )
then
end

rule "child" extends "parent"
when
    MyFact(...) from $var
then
end

   Regarding your other question, Drools allows you to automatically
disable/enable parent rule, cancel rules in a rule group after another rule
fires, etc. but what you want to do is not available declaratively. You will
need to add constraints for that in a similar way to Pavel's suggestion.

   []s
   Edson


2010/3/9 Moe Alkhafaji <moe.alkhafaji at medcpu.com>

> Thanks Pavel.  I was hoping for more of a transparent functionality
> supported by Drools than have my users add those control method calls. I am
> trying to make their rules as "control logic" blind as possible. But, I
> guess they would have to do that.
>
> Also, any idea on re-using an object from the parent rule? What is the
> syntax for using an object declared in the parent rule? Thanks.
>
>
> On Tue, Mar 9, 2010 at 11:25 AM, Pavel Tavoda <pavel.tavoda at gmail.com>wrote:
>
>> Aha, misunderstanding. Yes you can't use activation group if you want
>> execute more children rules. However you can use fact (Status) to
>> avoid evaluating parent rule. My suggestion:
>>
>> Rule DEFAULT
>> salience -100
>> if A and ! Status(done) then DEFAULT end
>>
>> Rule A
>> if A and B then SOMETHINGB; update(Status(done)) end
>>
>> Rule B
>> if A or B then SOMETHINGB; update(Status(done)) end
>>
>> Rule C
>> if A or C then SOMETHINGC; update(Status(done)) end
>>
>> At beginning insert Status with e.g. "ready". It's possible to use
>> instead of update also insert but because you can fire more children
>> rules it will be waste of memory.
>>
>> Hope this help
>>
>> Pavel
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>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>
>
>
> --
> Moe Alkhafaji
> Chief Technology Officer, MedCPU
> Phone: (630) 290-1113
> Email: cto at medcpu.com
>
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-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss by Red Hat @ www.jboss.com
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