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AMD64 マシンで Linux 用の SBCL を使用しています。関数 CONTROL-TEST は、描画 CANVAS と 2 つのスライド SCALE を含むウィンドウを作成します。UPPER-SLIDER と FORE-SLIDER のスライダー :VARIABLES は、それぞれ UPPER-THETA と FORE-THETA にバインドされるはずですが、更新コードは 0 以外は認識しません。別の関数で更新コードをテストしました。

(defun controltest ()
  "Test of a user-controlled robot arm"
  (with-ltk ()
    ; (make-instance 'scale :master fscale :from 0 :to 100  :length 150 )
    (let* ((upper-theta 0) (fore-theta 0)
       (upper-slider 
        (make-instance 'scale :from 0 :to 7 
               :length  360 :variable upper-theta))
       (fore-slider 
        (make-instance 'scale :from 0 :to 7
               :length  360 :variable fore-theta))
       (cnvs (make-instance 'canvas :width cnvs-width :height cnvs-height))
       (upper (manip:uctk-beam :cen-x 200 :cen-y 200 
                   :b-length 40 :b-width 20
                   :tk-cnvs cnvs))
       (fore (manip:uctk-beam :cen-x 0 :cen-y 40 ; relative to upper
                  :b-length 40 :b-width 20
                  :tk-cnvs cnvs))
       (slp-time 50))
      (labels ((update ()
         (draw upper nil) ; contains FORE, no need to draw separately
         (geo:set-member-theta upper 2 fore-theta)
         (geo:set-theta upper upper-theta)
         (after slp-time #'update)))
    (geo:add-geo upper fore) ; make FORE a member of UPPER
    (pack cnvs :fill :both :expand 1)
    (pack upper-slider :side :bottom)
    (pack fore-slider :side :bottom)
    (update)))))
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Please excuse me, it appears I did not perform my due diligence, this question was answered 3 years ago at the following location: http://permalink.gmane.org/gmane.lisp.ltk.user/329

The answer is that the name passed to :VARIABLE is not in fact updated automatically. Instead of messing with :VARIABLE, I pass a LAMBDA expression to the :COMMAND keyword; and therefore the following is the correct way:

(upper-slider 
        (make-instance 'scale :from 0 :to 7 
               :length  360 
               :command (lambda (val) (setq upper-theta val))))
(fore-slider 
        (make-instance 'scale :from 0 :to 7 
               :length  360 
               :command (lambda (val) (setq fore-theta val))))
于 2012-12-21T22:44:28.820 に答える