Arrows GUI

arrow-gui.ss

The teachpack arrow-gui.ss implements three functions:

control : -> symbol
to read out the current state of the msg field

view : (union string symbol) -> true
to display its argument in the message panel

modelT = (button% event% -> true)
connect : modelT modelT modelT modelT -> true
to connect four controllers with the four directions in the arrow window

Example:

> (define (make-model dir)
   (lambda (b e)
     (printf (format "~a" (control)))
     (view dir)))

> (connect
   (make-model "west")
   (make-model "east")
   (make-model "north")
   (make-model "south"))

Now click on the four arrows. The message field will contain the current direction, the print-out the prior contents of the message field.