;; FILE          "yasos-base.scm"
;; IMPLEMENTS    YASOS: Yet Another Scheme Object System
;; AUTHOR        Ken [dot] Dickey [at] Whidbey [dot] Com
;; DATE          1992 March 1
;; LAST UPDATED  1992 March 5
;; CHICKEN-PORT  2008 February 7

;; INSTANCES

(module yasos-base
  (export make-instance instance? instance-dispatcher)
  (import scheme)

  (define make-instance 'bogus)  ;; defined below
  (define instance?     'bogus)
  (define instance-dispatcher 'bogus)
  
  (let ((instance-tag "instance"))
        ;; Make a unique tag within a local scope.
        ;; No other data object is EQ? to this tag.
    (set! make-instance
    (lambda (dispatcher) (cons instance-tag dispatcher)))
    (set! instance?
	  (lambda (obj) (and (pair? obj) (eq? (car obj) instance-tag))))
    (set! instance-dispatcher
	  (lambda (inst) (cdr inst)))) )
      
;;;
;;; COPYRIGHT (c) 1992,2008 by Kenneth A Dickey, All rights reserved.
;;;
;;;Permission is hereby granted, free of charge, to any person
;;;obtaining a copy of this software and associated documentation
;;;files (the "Software"), to deal in the Software without
;;;restriction, including without limitation the rights to use,
;;;copy, modify, merge, publish, distribute, sublicense, and/or
;;;sell copies of the Software, and to permit persons to whom
;;;the Software is furnished to do so, subject to the following
;;;conditions:
;;;
;;;The above copyright notice and this permission notice shall
;;;be included in all copies or substantial portions of the Software.
;;;
;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
;;;EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
;;;OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
;;;NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
;;;HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
;;;WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
;;;FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
;;;OTHER DEALINGS IN THE SOFTWARE.