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source: branches/f4grobner/copy.lisp@ 3576

Last change on this file since 3576 was 3469, checked in by Marek Rychlik, 9 years ago

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File size: 3.2 KB
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1;;; -*- mode: lisp; package: maxima; syntax: common-lisp; base: 10 -*-
2;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
3;;;
4;;; copyright (c) 1999, 2002, 2009, 2015 marek rychlik <rychlik@u.arizona.edu>
5;;;
6;;; this program is free software; you can redistribute it and/or modify
7;;; it under the terms of the gnu general public license as published by
8;;; the free software foundation; either version 2 of the license, or
9;;; (at your option) any later version.
10;;;
11;;; this program 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
14;;; gnu general public license for more details.
15;;;
16;;; you should have received a copy of the gnu general public license
17;;; along with this program; if not, write to the free software
18;;; foundation, inc., 59 temple place - suite 330, boston, ma 02111-1307, usa.
19;;;
20;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
21
22(defpackage "COPY"
23 (:use :cl)
24 (:export "COPY-INSTANCE")
25 (:shadowing-import-from
26 #+openmcl-native-threads #:ccl
27 #+cmu #:pcl
28 #+sbcl #:sb-pcl
29 #+lispworks #:hcl
30 #+allegro #:mop
31 #+clisp #:clos
32 #:class-slots #:slot-definition-name)
33 (:documentation "Implements generic clone operation."))
34
35(in-package :copy)
36
37;; Source: http://stackoverflow.com/questions/11067899/is-there-a-generic-method-for-cloning-clos-objects
38;; NOTE: This is a shallow copy. Add an around method for classes which need deep copy of the slots.
39(defgeneric copy-instance (object &rest initargs &key &allow-other-keys)
40 (:method ((object cons) &rest initargs &key &allow-other-keys)
41 (declare (ignore initargs))
42 (copy-seq object))
43 (:documentation "Makes and returns a shallow copy of OBJECT.
44
45 An uninitialized object of the same class as OBJECT is allocated by
46 calling ALLOCATE-INSTANCE. For all slots returned by
47 CLASS-SLOTS, the returned object has the
48 same slot values and slot-unbound status as OBJECT.
49
50 REINITIALIZE-INSTANCE is called to update the copy with INITARGS.")
51 (:method ((object standard-object) &rest initargs &key &allow-other-keys)
52 (let* ((class (class-of object))
53 (copy (allocate-instance class)))
54 (dolist (slot-name (mapcar #'slot-definition-name (class-slots class)))
55 (when (slot-boundp object slot-name)
56 (setf (slot-value copy slot-name)
57 (slot-value object slot-name))))
58 (apply #'reinitialize-instance copy initargs))))
59
60#|
61;; A stripped-down version of shallow copy
62;; Source: http://stackoverflow.com/questions/11067899/is-there-a-generic-method-for-cloning-clos-objects
63(defun shallow-copy-object (original)
64 (let* ((class (class-of original))
65 (copy (allocate-instance class)))
66 (dolist (slot (mapcar #'slot-definition-name (class-slots class)))
67 (when (slot-boundp original slot)
68 (setf (slot-value copy slot)
69 (slot-value original slot))))
70 copy))
71|#
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