Amiga Format CD 41/Amiga Format CD41 (1999-06)(Future Publishing)(GB)[!][issue 1999-07].iso/-seriously_amiga-/programming/other/scm/slib/yasyn.scm

Text File | 1999-04-19 | 5KB | 202 lines

;;"yasyn.scm" YASOS in terms of "object.scm"
;;;From: [e-mail] (Wade Humeniuk)

(require 'object)

(define yasos:instance?     object?)
;; Removed (define yasos:make-instance 'bogus)  ;;
;; Removed (define-syntax YASOS:INSTANCE-DISPATCHER  ;; alias so compiler can inline for speed
;;   (syntax-rules () ((yasos:instance-dispatcher inst) (cdr inst))))
;; DEFINE-OPERATION

(define-syntax define-operation
  (syntax-rules ()
    ((define-operation (<name> <inst> <arg> ...) <exp1> <exp2> ...)
     ;;=>
     (define <name> (make-generic-method
             (lambda (<inst> <arg> ...) <exp1> <exp2> ...))))

    ((define-operation (<name> <inst> <arg> ...) ) ;; no body
     ;;=>
     (define-operation (<name> <inst> <arg> ...)
       (slib:error "Operation not handled"
           '<name>
           (format #f (if (yasos:instance? <inst>) "#<INSTANCE>" "~s")
               <inst>))))))

;; DEFINE-PREDICATE

(define-syntax define-predicate
  (syntax-rules ()
    ((define-predicate <name>)
     ;;=>
     (define <name> (make-generic-predicate)))))

;; OBJECT

(define-syntax object
  (syntax-rules ()
    ((object ((<name> <self> <arg> ...) <exp1> <exp2> ...) ...)
    ;;=>
     (let ((self (make-object)))
       (make-method! self <name> (lambda (<self> <arg> ...) <exp1> <exp2> ...))
       ...
       self))))

;; OBJECT with MULTIPLE INHERITANCE  {First Found Rule}

(define-syntax object-with-ancestors
  (syntax-rules ()
    ((object-with-ancestors ( (<ancestor1> <init1>) ... )
                ((<name> <self> <arg> ...) <exp1> <exp2> ...) ...)
    ;;=>
     (let* ((<ancestor1> <init1>)
        ...
        (self (make-object <ancestor1> ...)))
       (make-method! self <name> (lambda (<self> <arg> ...) <exp1> <exp2> ...))
       ...
       self))))

;; OPERATE-AS  {a.k.a. send-to-super}

; used in operations/methods

(define-syntax operate-as
  (syntax-rules ()
   ((operate-as <component> <op> <composit> <arg> ...) ;; What is <composit> ???
   ;;=>
    ((get-method <component> <op>) <composit> <arg> ...))))



;; SET & SETTER


(define-syntax set
  (syntax-rules ()
    ((set (<access> <index> ...) <newval>)
     ((yasos:setter <access>) <index> ... <newval>)
    )
    ((set <var> <newval>)
     (set! <var> <newval>)
    )
) )


(define yasos:add-setter    'bogus)
(define yasos:remove-setter-for 'bogus)

(define yasos:setter
  (let ( (known-setters (list (cons car set-car!)
                  (cons cdr set-cdr!)
                  (cons vector-ref vector-set!)
                  (cons string-ref string-set!))
     )
     (added-setters '())
       )

    (set! YASOS:ADD-SETTER
      (lambda (getter setter)
    (set! added-setters (cons (cons getter setter) added-setters)))
    )
    (set! YASOS:REMOVE-SETTER-FOR
      (lambda (getter)
    (cond
      ((null? added-setters)
       (slib:error "REMOVE-SETTER-FOR: Unknown getter" getter)
      )
      ((eq? getter (caar added-setters))
       (set! added-setters (cdr added-setters))
      )
      (else
        (let loop ((x added-setters) (y (cdr added-setters)))
          (cond
        ((null? y) (slib:error "REMOVE-SETTER-FOR: Unknown getter"
                       getter))
        ((eq? getter (caar y)) (set-cdr! x (cdr y)))
        (else (loop (cdr x) (cdr y)))
      ) ) )
     ) ) )

    (letrec ( (self
         (lambda (proc-or-operation)
           (cond ((assq proc-or-operation known-setters) => cdr)
             ((assq proc-or-operation added-setters) => cdr)
             (else (proc-or-operation self))) )
        ) )
      self)
) )



(define (yasos:make-access-operation <name>)
  (letrec ( (setter-dispatch
           (lambda (inst . args)
           (cond
             ((and (yasos:instance? inst)
               (get-method inst setter-dispatch))
               => (lambda (method) (apply method (cons inst args)))
             )
             (else #f)))
        )
        (self
           (lambda (inst . args)
          (cond
             ((eq? inst yasos:setter) setter-dispatch) ; for (setter self)
             ((and (yasos:instance? inst)
               (get-method inst self))
              => (lambda (method) (apply method (cons inst args)))
             )
             (else (slib:error "Operation not handled" <name> inst))
        )  )
        )
      )

      self
) )

(define-syntax define-access-operation
  (syntax-rules ()
    ((define-access-operation <name>)
     ;=>
     (define <name> (yasos:make-access-operation '<name>))
) ) )



;;---------------------
;; general operations
;;---------------------

(define-operation (yasos:print obj port)
  (format port
      ;; if an instance does not have a PRINT operation..
      (if (yasos:instance? obj) "#<INSTANCE>" "~s")
      obj
) )

(define-operation (yasos:size obj)
  ;; default behavior
  (cond
    ((vector? obj) (vector-length obj))
    ((list?   obj) (length obj))
    ((pair?   obj) 2)
    ((string? obj) (string-length obj))
    ((char?   obj) 1)
    (else
      (slib:error "Operation not supported: size" obj))
) )

(require 'format)

;;; exports:

(define print yasos:print)        ; print also in debug.scm
(define size yasos:size)
(define add-setter yasos:add-setter)
(define remove-setter-for yasos:remove-setter-for)
(define setter yasos:setter)

(provide 'oop)                ;in case we were loaded this way.
(provide 'yasos)