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1.13 An Arrow GUI: "arrow-gui.ss"

The teachpack provides operations for creating and manipulating an arrow GUI. We recommend using the world teachpack instead.

modelT (-> button% event% true)

A modelT is a function that accepts and ignores two arguments.

Reads out the current state of the message field.

(view s)  true
  s : (or/c string? symbol?)
Displays s in the message field.

(connect l r u d)  true
  l : modelT
  r : modelT
  u : modelT
  d : modelT
Connects four controllers with the four directions in the arrow window.

  ; Advanced
  (define (make-model dir)
     (lambda (b e)
         (view dir)
         (printf "~a ~n" (control)))))
     (make-model "left")
     (make-model "right")
     (make-model "up")
     (make-model "down"))
Now click on the four arrows. The message field contains the current direction, the print-out the prior contents of the message field.