[rules-users] New to rules engine - help in defining rules

[Edson Tirelli]

    Jeevan,

    You are right: the simplest way would be use "forall". 
Unfortunatelly it is only available in trunk.
    To do it in 3.0.x you will need either a helper attribute or a 
helper class. For instance, you may add a "branchLength" attribute to 
the tree and define 2 rules:

rule "define length"
when
     $t : Tree( branchLength == -1 )
     Branch( mytree == $t, $bl : branch_length )
then
     $t.setBranchLength( $bl.intValue() );
     modify( $t );
end

rule "check length"
when
    $t : Tree( $bl : branchLength != -1 )
    exists Branch( mytree == $t, branch_length != $bl )
then
    // do something because the branch has a different length
end

   There are several variations but you will need 2 rules to emulate this.
   Hopefully the new version will be out soon solving this kind of problem.

   []s
   Edson

Jeevan Tambuluri wrote:

> Hello all,
>
> I am looking for a way to define rules for the following problem:
>
> class Tree {
> ...
> }
>
> class Branch {
>    Tree  mytree;
>     int     branch_length;
> ...
> }
>
> Let's say I have a fact called Tree and another fact called Branch. 
> Brach identifies which tree it belongs to.
> Now, I want to write a rule to say that all branches in a tree must be 
> of same length.
> How do I do this with/without using accumulate or forall?
>
> Thanks a lot for any help,
>
> J
>
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> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>


-- 
 Edson Tirelli
 Software Engineer - JBoss Rules Core Developer
 Office: +55 11 3124-6000
 Mobile: +55 11 9218-4151
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