Re: [rules-users] New to rules engine - help in defining rules
Hi Edson,
My procedural mind is unable to see how a helper class gets the job
done. Could you elaborate?
Let's say I want to write a rule: The sum of lengths of all branches in
a tree must be more than 100.
Also, another question. I defined a rule to identify all trees that
have same length branches as follows:
rule "same length"
when
$t : Tree( $bl : branchLength != -1 )
exists not Branch( mytree == $t, branch_length != $bl )
then
// Print Tree object, because the branches have same length
end
When I call fireAllRules() on workingmemory object, I see this rule
triggering for tree objects with same length branches.
Now, let's say I have an assreted tree object with two branches with
different lengths. Rule "check length" would fire for it. Then I go and
modify working memory by setting the branch length of Branch object to
same value as the other Branch object. I expected the "same length" rule
to fire and print the Tree object, but that didnot happen. I simply
called workingMemory.modifyOject() by passing the fact handle of the
Branch object and the same old Branch object with modified branch length.
Thanks
Jeevan
Edson Tirelli wrote:
Jeevan,
Same idea. You need a helper class that will accumulate your value.
[]s
Edson
Jeevan Tambuluri wrote:
> Thanks Edson! The rule pattern you suggested works for me. Any such
> pattern to simulate "accumulate" in 3.0.x?
>
> Jeevan
>
> Edson Tirelli wrote:
>
>>
>> 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
>>>
>>> _______________________________________________
>>> rules-users mailing list
>>> rules-users(a)lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>
>>
>>
>
>
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