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+;;; installed-scm-file
+
+;;;; Copyright (C) 1999, 2000 Free Software Foundation, Inc.
+;;;;
+;;;; This program is free software; you can redistribute it and/or modify
+;;;; it under the terms of the GNU General Public License as published by
+;;;; the Free Software Foundation; either version 2, or (at your option)
+;;;; any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this software; see the file COPYING. If not, write to
+;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+;;;; Boston, MA 02111-1307 USA
+;;;;
+
+
+;;;; This software is a derivative work of other copyrighted softwares; the
+;;;; copyright notices of these softwares are placed in the file COPYRIGHTS
+;;;;
+;;;; This file is based upon composite-slot.stklos from the STk
+;;;; distribution by Erick Gallesio <eg@unice.fr>.
+;;;;
+
+(define-module (oop goops composite-slot)
+ :use-module (oop goops))
+
+(export <composite-class>)
+
+;;;
+;;; (define-class CLASS SUPERS
+;;; ...
+;;; (OBJECT ...)
+;;; ...
+;;; (SLOT #:allocation #:propagated
+;;; #:propagate-to '(PROPAGATION ...))
+;;; ...
+;;; #:metaclass <composite-class>)
+;;;
+;;; PROPAGATION ::= OBJECT | (OBJECT TARGETSLOT)
+;;;
+;;; The slot SLOT will be propagated to the slot TARGETSLOT in the object
+;;; stored in slot OBJECT. If TARGETSLOT is omitted, assume that the target
+;;; slot is named SLOT.
+;;;
+
+(define-class <composite-class> (<class>))
+
+(define-method compute-get-n-set ((class <composite-class>) slot)
+ (if (eq? (slot-definition-allocation slot) #:propagated)
+ (compute-propagated-get-n-set slot)
+ (next-method)))
+
+(define (compute-propagated-get-n-set s)
+ (let ((prop (get-keyword #:propagate-to (cdr s) #f))
+ (s-name (slot-definition-name s)))
+
+ (if (not prop)
+ (goops-error "Propagation not specified for slot ~S" s-name))
+ (if (not (pair? prop))
+ (goops-error "Bad propagation list for slot ~S" s-name))
+
+ (let ((objects (map (lambda (p) (if (pair? p) (car p) p)) prop))
+ (slots (map (lambda (p) (if (pair? p) (cadr p) s-name)) prop)))
+ (let ((first-object (car objects))
+ (first-slot (car slots)))
+ (list
+ ;; The getter
+ (lambda (o)
+ (slot-ref (slot-ref o first-object) first-slot))
+
+ ;; The setter
+ (if (null? (cdr objects))
+ (lambda (o v)
+ (slot-set! (slot-ref o first-object) first-slot v))
+ (lambda (o v)
+ (for-each (lambda (object slot)
+ (slot-set! (slot-ref o object) slot v))
+ objects
+ slots))))))))