Un peu de refactor.

grunt.rkt

@@ -1,8 +1,20 @@
 #lang racket/gui
 
+;; Prepare a canvas
+(define (get-my-canvas on-mouse on-key on-paint)
+  (define canvas '())
+  (define my-canvas% (class canvas%
+                       (define/override (on-event ev) (on-mouse ev canvas))
+                       (define/override (on-char ev) (on-key ev canvas))
+                       (super-new)))
+  (define frame (new frame% [label "Grunt"] [width 200] [height 200]))
+  (set! canvas (new my-canvas% [parent frame] [paint-callback on-paint]))
+  (lambda ()
+    (send frame show #t)))
+
+;; Pens
 (define black-pen (make-object pen% "BLACK" 1 'solid))
 (define transparent-brush (make-object brush% "BLACK" 'transparent))
-
 (define bloc-border-pen black-pen)
 (define bloc-fill-brush transparent-brush)
 
@@ -13,26 +25,19 @@
   (send dc set-brush bloc-fill-brush)
   (send dc draw-rectangle 100 test-block-y 10 10))
 
-(define (mouse-ev ev)
+(define (mouse-ev ev canvas)
   (display (send ev get-event-type))
   (display " ")
   (display (send ev get-x))
   (display " ")
   (displayln (send ev get-y)))
 
-(define (keyboard-ev ev)
+(define (keyboard-ev ev canvas)
   (when (eq? (send ev get-key-code) 'down)
     (set! test-block-y (+ test-block-y 10))
     (send (send canvas get-dc) clear)
     (send canvas on-paint)))
-      
-(define my-canvas% (class canvas%
-                     (define/override (on-event ev) (mouse-ev ev))
-                     (define/override (on-char ev) (keyboard-ev ev))
-                     (super-new)))
 
-(define frame (new frame% [label "Grunt"] [width 200] [height 200]))
-(define canvas (new my-canvas% [parent frame] [paint-callback redraw]))
+(define grunt (get-my-canvas mouse-ev keyboard-ev redraw))
 
-(define (grunt)
-  (send frame show #t))
+(define world '())