[rules-users] "Not" Non-Existential Quantifier

[Edson Tirelli]

   Oh, I see.

   Unfortunately in this case, there is nothing we can do about it, because
the rules are behaving exactly as they were supposed to behave:

NegativeResult(applicant == $applicant)

   As you can see, they are telling the application to use the equals
comparison in the constraint:

applicant == $applicant

   A fact should not change it's identity once it is asserted, so, either
you use a constant "equals()/hashcode()" implementation, or you use
constraints on an immutable ID:

NegativeResult(applicantId == $applicant.id)

   You can also fallback to java "identity" check by using eval, but it is
ugly... :)

NegativeResult( eval( applicant == $applicant) )

   []s
   Edson


2008/8/4 <ringsah at comcast.net>

>  Edson,
>
> I finally succeeded in coming up with a simple test case that shows the
> problem. I have attached the necessary files, which include a test case,
> three fact objects, and the drl.
>
> One key to this test are the fact that the Applicant fact object has an
> "equals" method that tests for equality of its attributes, rather than
> identity. A second key is that the applicant object is updated after it is
> inserted.
>
> It appears that what is happening is that an activation is created for the
> rule that uses "not" when the applicant is inserted. Then, when the
> applicant is updated, a second activation is created for that rule. It
> should be cancelling the previous activation, but doesn't find it because
> the Applicant instance no longer "equals" the fact object that caused the
> activation.
>
> Thanks!
> -Hans
>
> -------------- Original message --------------
> From: "Edson Tirelli" <tirelli at post.com>
>
>    Hans,
>
>    Your reasoning is correct. There should not be 2 instances of
> ApplicantStatus in the working memory.
>
>    Can you provide a test case showing the problem? we have test cases here
> using "not" and logical assertions, and it works properly.
>
>    Thanks,
>        Edson
>
> 2008/7/31 <ringsah at comcast.net>
>
>>  How is "
>> not" supposed to work with insertLogical? Assume I have two different
>> rules whose conditions are mutually exclusive, like the following:*
>>
>> rule
>> *"Rule One"
>>
>> *when*
>>
>> not NegativeResult()
>>
>> *then*
>>
>> *insertLogical*(new ApplicantStatus("Approved"));*
>>
>> end
>> **
>>
>> rule
>> *"Rule Two"
>>
>> *when*
>>
>> NegativeResult()
>>
>> *then*
>>
>> *insertLogical*(new ApplicantStatus("Denied"));*
>>
>> end
>> *
>>
>> Assume that the above two rules are the only way an
>> ApplicantStatus fact can be inserted into working memory. I would expect,
>> after all rules are run, that it would be impossible for there to be one
>> ApplicantStatus with "Approved" as its reason, and another with "Denied"as its reason, in the working memory.
>>
>> I would expect that, before any
>> NegativeResult is inserted, that rule one could run, and insert an
>> ApplicantStatus fact with an "Approved" reason. Then, after a
>> NegativeResult is inserted, that rule two could run, and insert an
>> ApplicantStatus fact with a "Denied" reason. At this point I would expect
>> that the original ApplicantStatus fact, with an "Approved" reason, would
>> be retracted, since the conditions under which it was inserted are no lon!
>> ger true.
>>
>> This is not what I am observing, however. I am finding
>> ApplicantStatus facts with both reasons in working memory at the end of
>> the rules run. Should "not" work as I expect with regard to inserting a fact
>> via insertLogical()? Or is this a known limitation, or simply the way it
>> is designed to work?
>>
>> Thanks,
>>
>> -Hans
>>
>> _______________________________________________
>> rules-users mailing list
>> 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
>
>
>
> ---------- Mensagem encaminhada ----------
> From: ringsah at comcast.net
> To: Rules Users List <rules-users at lists.jboss.org>
> Date: Mon, 04 Aug 2008 13:49:37 +0000
> Subject: Re: [rules-users] "Not" Non-Existential Quantifier
>
>
> ---------- Mensagem encaminhada ----------
> From: "Edson Tirelli" <tirelli at post.com>
> To: "Rules Users List" <rules-users at lists.jboss.org>
> Date: Thu, 31 Jul 2008 17:41:39 +0000
> Subject: Re: [rules-users] "Not" Non-Existential Quantifier
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>


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