[rules-users] Re: drools 5.0.0-SNAPSHOT Maven repository broken?

[Geoffrey De Smet]

tim tim schreef:

> where i got stuck for quite some time was this:
> 
> http://www.nabble.com/Questions-about-logically-justified-objects-ts14788904.html#a14790335

I am convinced that:
   2) Penalty's equals/hashcode uses both "cause" and "weight"?
   then 3) happens: Keep Penalty(10), add Penalty(5)
is an issue in drools core and instead 2) should happen:
   Remove Penalty(10), add Penalty(5)
because Penalty(10) is no longer true

I am going to make a testcase to isolate the problem and make it more 
transparent that it is indeed an issue. And then try to convince Mark 
and Edson that it's an issue :)

> 
> and i could not find how you solved this problem in the end.

which the HACK indeed that you quothed below:
   the hack causes the rule to no longer apply (retracting the 
ConstraintOccurrence), after which it then refires.

> 
> i solved the problem of improving constraints for the same causes that
> differ in hashCode by retracting the old fact before inserting the new
> one.
> but it takes quite some overhead to be able to do so. i could post my
> code if anyone is interested.
> 
> unfortunately i could not find in your samples how you handle such a scenario.
> 
> does the "HACK" part of this rule have something to do with it?
> 
> from curriculumCourseScoreRules.drl
> 
> // MinimumWorkingDays: The lectures of each course must be spread into
> a minimum number of days.
> // Each day below the minimum counts as 5 points of penalty.
> rule "minimumWorkingDays"
>     when
>         $course : Course($minWorkingDaySize : minWorkingDaySize);
>         $dayCount : Number(intValue < $minWorkingDaySize) from accumulate(
>             $day : Day()
>             and exists Lecture(course == $course, day == $day),
>             count($day)
>         );
>         // HACK to fix wierd truth maintance behavior in drools
>         // because making weight part of the equals/hashcode doesn't cut it
>         not IntConstraintOccurrence(
>             ruleId == "minimumWorkingDays",
>             constraintType == ConstraintType.NEGATIVE_SOFT,
>             causes contains $course,
>             eval(weight != (($minWorkingDaySize - $dayCount.intValue()) * 5))
>         );
>         // An uninitialized schedule should have no constraints broken
>         exists Lecture(course == $course);
>     then
>         insertLogical(new
> IntConstraintOccurrence("minimumWorkingDays",
> ConstraintType.NEGATIVE_SOFT,
>                 (($minWorkingDaySize - $dayCount.intValue()) * 5),
>                 $course));
> end
> 
> but the hack makes the rule not fire at all, when it had fired before.
> even if the error has improved by now.
> 

Feed back is always welcome :)

With kind regards,
Geoffrey De Smet