module/oop/goops/active-slot.scm

   1 ;;; installed-scm-file
   2
   3 ;;;;    Copyright (C) 1999, 2001, 2006, 2009 Free Software Foundation, Inc.
   4 ;;;;
   5 ;;;; This library is free software; you can redistribute it and/or
   6 ;;;; modify it under the terms of the GNU Lesser General Public
   7 ;;;; License as published by the Free Software Foundation; either
   8 ;;;; version 3 of the License, or (at your option) any later version.
   9 ;;;;
  10 ;;;; This library is distributed in the hope that it will be useful,
  11 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 ;;;; Lesser General Public License for more details.
  14 ;;;;
  15 ;;;; You should have received a copy of the GNU Lesser General Public
  16 ;;;; License along with this library; if not, write to the Free Software
  17 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18 ;;;;
  19 \f
  20
  21 ;;;; This software is a derivative work of other copyrighted softwares; the
  22 ;;;; copyright notices of these softwares are placed in the file COPYRIGHTS
  23 ;;;;
  24 ;;;; This file is based upon active-slot.stklos from the STk
  25 ;;;; distribution by Erick Gallesio <eg@unice.fr>.
  26 ;;;;
  27
  28 (define-module (oop goops active-slot)
  29   :use-module (oop goops internal)
  30   :export (<active-class>))
  31
  32 (define-class <active-class> (<class>))
  33
  34 (define-method (compute-get-n-set (class <active-class>) slot)
  35   (if (eq? (slot-definition-allocation slot) #:active)
  36       (let* ((index       (slot-ref class 'nfields))
  37              (s           (cdr slot))
  38              (before-ref  (get-keyword #:before-slot-ref  s #f))
  39              (after-ref   (get-keyword #:after-slot-ref   s #f))
  40              (before-set! (get-keyword #:before-slot-set! s #f))
  41              (after-set!  (get-keyword #:after-slot-set!  s #f))
  42              (unbound     (make-unbound)))
  43         (slot-set! class 'nfields (+ index 1))
  44         (list (lambda (o)
  45                 (if before-ref
  46                     (if (before-ref o)
  47                         (let ((res (%fast-slot-ref o index)))
  48                           (and after-ref (not (eqv? res unbound)) (after-ref o))
  49                           res)
  50                         (make-unbound))
  51                     (let ((res (%fast-slot-ref o index)))
  52                       (and after-ref (not (eqv? res unbound)) (after-ref o))
  53                       res)))
  54
  55               (lambda (o v)
  56                 (if before-set!
  57                     (if (before-set! o v)
  58                         (begin
  59                           (%fast-slot-set! o index v)
  60                           (and after-set! (after-set! o v))))
  61                     (begin
  62                       (%fast-slot-set! o index v)
  63                       (and after-set! (after-set! o v)))))))
  64       (next-method)))