module/oop/goops/composite-slot.scm

   1 ;;; installed-scm-file
   2
   3 ;;;;    Copyright (C) 1999, 2000, 2001, 2006 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 2.1 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 composite-slot.stklos from the STk
  25 ;;;; distribution by Erick Gallesio <eg@unice.fr>.
  26 ;;;;
  27
  28 (define-module (oop goops composite-slot)
  29   :use-module (oop goops)
  30   :export (<composite-class>))
  31
  32 ;;;
  33 ;;; (define-class CLASS SUPERS
  34 ;;;   ...
  35 ;;;   (OBJECT ...)
  36 ;;;   ...
  37 ;;;   (SLOT #:allocation #:propagated
  38 ;;;         #:propagate-to '(PROPAGATION ...))
  39 ;;;   ...
  40 ;;;   #:metaclass <composite-class>)
  41 ;;;
  42 ;;; PROPAGATION ::= OBJECT | (OBJECT TARGETSLOT)
  43 ;;;
  44 ;;; The slot SLOT will be propagated to the slot TARGETSLOT in the object
  45 ;;; stored in slot OBJECT.  If TARGETSLOT is omitted, assume that the target
  46 ;;; slot is named SLOT.
  47 ;;;
  48
  49 (define-class <composite-class> (<class>))
  50
  51 (define-method (compute-get-n-set (class <composite-class>) slot)
  52   (if (eq? (slot-definition-allocation slot) #:propagated)
  53       (compute-propagated-get-n-set slot)
  54       (next-method)))
  55
  56 (define (compute-propagated-get-n-set s)
  57   (let ((prop           (get-keyword #:propagate-to (cdr s) #f))
  58         (s-name         (slot-definition-name s)))
  59
  60     (if (not prop)
  61         (goops-error "Propagation not specified for slot ~S" s-name))
  62     (if (not (pair? prop))
  63         (goops-error "Bad propagation list for slot ~S" s-name))
  64
  65     (let ((objects (map (lambda (p) (if (pair? p) (car p) p)) prop))
  66           (slots (map (lambda (p) (if (pair? p) (cadr p) s-name)) prop)))
  67       (let ((first-object (car objects))
  68             (first-slot (car slots)))
  69         (list
  70          ;; The getter
  71          (lambda (o)
  72            (slot-ref (slot-ref o first-object) first-slot))
  73
  74          ;; The setter
  75          (if (null? (cdr objects))
  76              (lambda (o v)
  77                (slot-set! (slot-ref o first-object) first-slot v))
  78              (lambda (o v)
  79                (for-each (lambda (object slot)
  80                            (slot-set! (slot-ref o object) slot v))
  81                          objects
  82                          slots))))))))