;; This file contains excerpts from the textbook Concrete
;; Abstractions: An Introduction to Computer Science Using Scheme, by
;; Max Hailperin, Barbara Kaiser, and Karl Knight, Copyright (c) 1998
;; by Brooks/Cole Publishing Company. This file may not be reproduced
;; or redistributed other than for use with that textbook.

;; Chapter 14: Object-Oriented Programming

;; 14.5  An Application: Adventures in the Imaginary Land of Gack

;; The "registry" is an object that keeps track of all
;; the auto-person objects that need to be given an
;; opportunity to act.

(define registry (make-registry))

;; Here we define the places in the imaginary world of Gack

(define food-service (make-place 'food-service))
(define PO (make-place 'PO))
(define alumni-hall (make-place 'alumni-hall))
(define chamber-of-wizards (make-place 'chamber-of-wizards))
(define library (make-place 'library))
(define good-ship-olin (make-place 'good-ship-olin))
(define lounge (make-place 'lounge))
(define computer-lab (make-place 'computer-lab))
(define offices (make-place 'offices))
(define dormitory (make-place 'dormitory))
(define pond (make-place 'pond))

;; One-way paths connect individual places in the world.

(place/add-new-neighbor food-service 'down PO)
(place/add-new-neighbor PO 'south alumni-hall)
(place/add-new-neighbor alumni-hall 'north food-service)
(place/add-new-neighbor alumni-hall 'east chamber-of-wizards)
(place/add-new-neighbor alumni-hall 'west library)
(place/add-new-neighbor chamber-of-wizards 'west alumni-hall)
(place/add-new-neighbor chamber-of-wizards 'south dormitory)
(place/add-new-neighbor dormitory 'north chamber-of-wizards)
(place/add-new-neighbor dormitory 'west good-ship-olin)
(place/add-new-neighbor library 'east alumni-hall)
(place/add-new-neighbor library 'south good-ship-olin)
(place/add-new-neighbor good-ship-olin 'north library)
(place/add-new-neighbor good-ship-olin 'east dormitory)
(place/add-new-neighbor good-ship-olin 'up lounge)
(place/add-new-neighbor lounge 'west computer-lab)
(place/add-new-neighbor lounge 'south offices)
(place/add-new-neighbor computer-lab 'east lounge)
(place/add-new-neighbor offices 'north lounge)

;; We define persons as follows:

;; We've chosen to define max-the-person rather than
;; redefining max, which is predefined in Scheme to
;; be a procedure for finding the largest of its numeric
;; arguments.
(define max-the-person
  (make-auto-person 'max offices 2))

(define karl
  (make-auto-person 'karl computer-lab 4))

(define barbara
  (make-witch 'barbara offices 3))

(define elvee
  (make-wizard 'elvee chamber-of-wizards 1))

(define player
  (make-person 'player dormitory))

;; and now we'll strew some scrolls around:

(define scroll-of-enlightenment
  (make-scroll 'scroll-of-enlightenment))
(place/gain library scroll-of-enlightenment)

(for-each (lambda (title)
            (place/gain library
                        (make-scroll title)))
          '(crime-and-punishment war-and-peace
                                 iliad
                                 collected-works-of-rilke))

(define unix-programmers-manual
  (make-scroll 'unix-programmers-manual))
(place/gain computer-lab unix-programmers-manual)

(define next-users-reference
  (make-scroll 'next-users-reference))
(place/gain computer-lab next-users-reference)