module/oop/goops/active-slot.scm

   1 ;;; installed-scm-file
   2
   3 ;;;; Copyright (C) 1999, 2001, 2006, 2009, 2015 Free Software Foundation, Inc.
   4 ;;;; Copyright (C) 1993-1998 Erick Gallesio - I3S-CNRS/ESSI <eg@unice.fr>
   5 ;;;;
   6 ;;;; This library is free software; you can redistribute it and/or
   7 ;;;; modify it under the terms of the GNU Lesser General Public
   8 ;;;; License as published by the Free Software Foundation; either
   9 ;;;; version 3 of the License, or (at your option) any later version.
  10 ;;;;
  11 ;;;; This library is distributed in the hope that it will be useful,
  12 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 ;;;; Lesser General Public License for more details.
  15 ;;;;
  16 ;;;; You should have received a copy of the GNU Lesser General Public
  17 ;;;; License along with this library; if not, write to the Free Software
  18 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19 ;;;;
  20
  21 \f
  22 ;;;;
  23 ;;;; This file was based upon active-slot.stklos from the STk distribution
  24 ;;;; version 4.0.1 by Erick Gallesio <eg@unice.fr>.
  25 ;;;;
  26
  27 (define-module (oop goops active-slot)
  28   :use-module (oop goops internal)
  29   :export (<active-class>))
  30
  31 (define-class <active-class> (<class>))
  32
  33 (define-method (compute-get-n-set (class <active-class>) slot)
  34   (if (eq? (slot-definition-allocation slot) #:active)
  35       (let* ((index       (slot-ref class 'nfields))
  36              (s           (cdr slot))
  37              (before-ref  (get-keyword #:before-slot-ref  s #f))
  38              (after-ref   (get-keyword #:after-slot-ref   s #f))
  39              (before-set! (get-keyword #:before-slot-set! s #f))
  40              (after-set!  (get-keyword #:after-slot-set!  s #f))
  41              (unbound     *unbound*))
  42         (slot-set! class 'nfields (+ index 1))
  43         (list (lambda (o)
  44                 (if before-ref
  45                     (if (before-ref o)
  46                         (let ((res (struct-ref o index)))
  47                           (and after-ref (not (eqv? res unbound)) (after-ref o))
  48                           res)
  49                         *unbound*)
  50                     (let ((res (struct-ref o index)))
  51                       (and after-ref (not (eqv? res unbound)) (after-ref o))
  52                       res)))
  53
  54               (lambda (o v)
  55                 (if before-set!
  56                     (if (before-set! o v)
  57                         (begin
  58                           (struct-set! o index v)
  59                           (and after-set! (after-set! o v))))
  60                     (begin
  61                       (struct-set! o index v)
  62                       (and after-set! (after-set! o v)))))))
  63       (next-method)))