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protegejess

Using slot-insert$ in Jess Tab /Protege

The following code in the Jess Tab continuously inserts the same instance into a multivalued slot.

(defrule satisfactibleEstudio
    (object (is-a Estudio)
        (OBJECT ?user)
        (nombre ?name)
        (preferencias_minimas ?pref))

    (object (is-a Chalet)
        (OBJECT ?viv)
        (precio ?p&: (and
                        (>= ?p (slot-get ?pref precio_minimo))
                        (<= ?p (slot-get ?pref precio_maximo))))
        (tamanno ?t&: (and
                        (>= ?t (slot-get ?pref tamanno_minimo))
                        (<= ?t (slot-get ?pref tamanno_maximo))))
        (componentes $?comp&: (>= (get-dorms $?comp) (slot-get ?pref dormitorios))))
=>
    (slot-insert$ ?user satisfactibles 1 ?viv))

However, if I replace the slot-insert$ function by a printout it works as intended. What am I doing wrong?

Update: So apparently it's continuously inserting the same instance into the slot, however with a printout it only prints once per match.

Solution

  • See the Jess manual about modifying a fact on the right hand side:

    If a rule includes the declaration (declare (no-loop TRUE)), then nothing that a rule does while firing can cause the immediate reactivation of the same rule; i.e., if a no-loop rule matches a fact, and the rule modifies that same fact such that the fact still matches, the rule will not be put back on the agenda, avoiding an infinite loop.