;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-advanced-reader.ss" "lang")((modname fish) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ())))
(require htdp/gui)

(define-struct fish (weight))

(define (create-fish init-size)
  (local [
          ; The model:
          (define FISH (make-fish init-size))
          ; feed : num -> num
          ;  ...
          (define (feed n)
            (begin
              (set-fish-weight! FISH (+ n (fish-weight FISH)))
              (fish-weight FISH)))
          
          ; The view:
          (define msg (make-message (number->string (fish-weight FISH))))
          ; The control:
          (define (feed-button n)
            (make-button (string-append "Feed " (number->string n))
                         (lambda (evt)
                           (draw-message
                            msg
                            (number->string (feed n))))))]
    (begin
      (create-window
       (list (list msg) (list (feed-button 1) (feed-button 3))))
      FISH)))

(define samuel (create-fish 3))
(define sam samuel)
(define gil (create-fish 7))