oop/goops/active-slot.scm

   1 ;;; installed-scm-file
   2
   3 ;;;;    Copyright (C) 1999, 2001 Free Software Foundation, Inc.
   4 ;;;;
   5 ;;;; This program is free software; you can redistribute it and/or modify
   6 ;;;; it under the terms of the GNU General Public License as published by
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   8 ;;;; any later version.
   9 ;;;;
  10 ;;;; This program is distributed in the hope that it will be useful,
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  12 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 ;;;; GNU General Public License for more details.
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  20 ;;;; As a special exception, the Free Software Foundation gives permission
  21 ;;;; for additional uses of the text contained in its release of GUILE.
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  33 ;;;; Free Software Foundation under the name GUILE.  If you copy
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  43 ;;;;
  44 \f
  45
  46 ;;;; This software is a derivative work of other copyrighted softwares; the
  47 ;;;; copyright notices of these softwares are placed in the file COPYRIGHTS
  48 ;;;;
  49 ;;;; This file is based upon active-slot.stklos from the STk
  50 ;;;; distribution by Erick Gallesio <eg@unice.fr>.
  51 ;;;;
  52
  53 (define-module (oop goops active-slot)
  54   :use-module (oop goops internal))
  55
  56 (export <active-class>)
  57
  58 (define-class <active-class> (<class>))
  59
  60 (define-method (compute-get-n-set (class <active-class>) slot)
  61   (if (eq? (slot-definition-allocation slot) #:active)
  62       (let* ((index       (slot-ref class 'nfields))
  63              (name        (car slot))
  64              (s           (cdr slot))
  65              (env         (class-environment class))
  66              (before-ref  (get-keyword #:before-slot-ref  s #f))
  67              (after-ref   (get-keyword #:after-slot-ref   s #f))
  68              (before-set! (get-keyword #:before-slot-set! s #f))
  69              (after-set!  (get-keyword #:after-slot-set!  s #f))
  70              (unbound     (make-unbound)))
  71         (slot-set! class 'nfields (+ index 1))
  72         (list (lambda (o)
  73                 (if before-ref
  74                     (if (before-ref o)
  75                         (let ((res (%fast-slot-ref o index)))
  76                           (and after-ref (not (eqv? res unbound)) (after-ref o))
  77                           res)
  78                         (make-unbound))
  79                     (let ((res (%fast-slot-ref o index)))
  80                       (and after-ref (not (eqv? res unbound)) (after-ref o))
  81                       res)))
  82
  83               (lambda (o v)
  84                 (if before-set!
  85                     (if (before-set! o v)
  86                         (begin
  87                           (%fast-slot-set! o index v)
  88                           (and after-set! (after-set! o v))))
  89                     (begin
  90                       (%fast-slot-set! o index v)
  91                       (and after-set! (after-set! o v)))))))
  92       (next-method)))