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.

(control) → symbol?

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.

Example:

; Advanced

(define (make-model dir)

(lambda (b e)

(begin

(view dir)

(printf "~a ~n" (control)))))

(connect

(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.