6.5.3.2 Interleaved in a Single Thread

By binding *inferencing-state* around specific KnowledgeWorks operations in a function as in the example below, multiple inferencing states can be maintained within a single thread.

(defun test-stepping-single-context ()

  (let ((state1 (make-inferencing-state 'state1))

        (state2 (make-inferencing-state 'state2)))

    (unwind-protect

        (progn

          (let ((*inferencing-state* state1))

            (make-instance 'step-controller

                           :kb-name 'stepper-one-a))

          (let ((*inferencing-state* state2))

            (make-instance 'step-controller

                           :kb-name 'stepper-one-b))

          (loop repeat 10

                do

                (let ((*inferencing-state* state1))

                  (infer))

                (let ((*inferencing-state* state2))

                  (infer))))

      (destroy-inferencing-state state1)

      (destroy-inferencing-state state2))))

KnowledgeWorks and Prolog User Guide (Unix version) - 6 Dec 2011