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13.4.4 Setting the Duplication Behavior of Facts

This function sets fact duplication behavior. When this behavior is disabled (FALSE by default), asserting a duplicate of a fact already in the fact-list produces no effect. When enabled (TRUE), the duplicate fact is asserted with a new fact-index. The return value for this function is the old value for the behavior.

Syntax

(set-fact-duplication <boolean-expression>)

Example

CLIPS> (get-fact-duplication)
FALSE
CLIPS> (watch all)
CLIPS> (assert (a))
==> f-0     (a)
<Fact-0>
CLIPS> (assert (a))
FALSE
CLIPS> (set-fact-duplication TRUE)
FALSE
CLIPS> (assert (a))
==> f-1     (a)
<Fact-1>
CLIPS>


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