Initial checkin

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+;;; *************************************************************************
+;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
+;;; All rights reserved.
+;;;
+;;; Use and copying of this software and preparation of derivative works
+;;; based upon this software are permitted.  Any distribution of this
+;;; software or derivative works must comply with all applicable United
+;;; States export control laws.
+;;; 
+;;; This software is made available AS IS, and Xerox Corporation makes no
+;;; warranty about the software, its performance or its conformity to any
+;;; specification.
+;;; 
+;;; Any person obtaining a copy of this software is requested to send their
+;;; name and post office or electronic mail address to:
+;;;   CommonLoops Coordinator
+;;;   Xerox PARC
+;;;   3333 Coyote Hill Rd.
+;;;   Palo Alto, CA 94304
+;;; (or send Arpanet mail to CommonLoops-Coordinator.pa@Xerox.arpa)
+;;;
+;;; Suggestions, comments and requests for improvements are also welcome.
+;;; *************************************************************************
+;;;
+
+;;; Modifications for better AMOP conformance
+;;; Copyright (C) 2001 Espen S. Johnsen <esj@stud.cs.uit.no>
+
+(in-package "PCL")
+
+;;;; Adding initargs parameter to change-class
+
+(defun change-class-internal (instance new-class initargs)
+  (let* ((old-class (class-of instance))
+        (copy (allocate-instance new-class))
+        (new-wrapper (get-wrapper copy))
+        (old-wrapper (class-wrapper old-class))
+        (old-layout (wrapper-instance-slots-layout old-wrapper))
+        (new-layout (wrapper-instance-slots-layout new-wrapper))
+        (old-slots (get-slots instance))
+        (new-slots (get-slots copy))
+        (old-class-slots (wrapper-class-slots old-wrapper)))
+
+    ;;
+    ;; "The values of local slots specified by both the class Cto and
+    ;; Cfrom are retained.  If such a local slot was unbound, it remains
+    ;; unbound."
+    ;;     
+    (iterate ((new-slot (list-elements new-layout))
+             (new-position (interval :from 0)))
+      (let ((old-position (posq new-slot old-layout)))
+       (when old-position
+         (setf (instance-ref new-slots new-position)
+               (instance-ref old-slots old-position)))))
+
+    ;;
+    ;; "The values of slots specified as shared in the class Cfrom and
+    ;; as local in the class Cto are retained."
+    ;;
+    (iterate ((slot-and-val (list-elements old-class-slots)))
+      (let ((position (posq (car slot-and-val) new-layout)))
+       (when position
+         (setf (instance-ref new-slots position) (cdr slot-and-val)))))
+
+    ;; Make the copy point to the old instance's storage, and make the
+    ;; old instance point to the new storage.
+    (swap-wrappers-and-slots instance copy)
+
+    (apply #'update-instance-for-different-class copy instance initargs)
+    instance))
+
+
+(fmakunbound 'change-class)
+(defgeneric change-class (instance new-class &rest initargs))
+
+(defmethod change-class ((instance standard-object)
+                        (new-class standard-class)
+                        &rest initargs)
+  (change-class-internal instance new-class initargs))
+
+(defmethod change-class ((instance funcallable-standard-object)
+                        (new-class funcallable-standard-class)
+                        &rest initargs)
+  (change-class-internal instance new-class initargs))
+
+(defmethod change-class ((instance standard-object)
+                        (new-class funcallable-standard-class)
+                        &rest initargs)
+  (error "Can't change the class of ~S to ~S~@
+          because it isn't already an instance with metaclass ~S."
+        instance new-class 'standard-class))
+
+(defmethod change-class ((instance funcallable-standard-object)
+                        (new-class standard-class)
+                        &rest initargs)
+  (error "Can't change the class of ~S to ~S~@
+          because it isn't already an instance with metaclass ~S."
+        instance new-class 'funcallable-standard-class))
+
+(defmethod change-class ((instance t) (new-class symbol) &rest initargs)
+  (change-class instance (find-class new-class) initargs))
+
+
+;;;; Make the class finalization protocol behave as specified in AMOP
+
+(defmethod ensure-class-using-class (name (class pcl-class) &rest args &key)
+  (multiple-value-bind (meta initargs)
+      (ensure-class-values class args)
+    (if (eq (class-of class) meta)
+       (apply #'reinitialize-instance class initargs)
+      (apply #'change-class class meta initargs))
+    (setf (find-class name) class)
+    (inform-type-system-about-class class name)
+    class))
+
+(defmethod finalize-inheritance ((class std-class))
+  (dolist (super (class-direct-superclasses class))
+    (unless (class-finalized-p super) (finalize-inheritance super)))
+  (update-cpl class (compute-class-precedence-list class))
+  (update-slots class (compute-slots class))
+  (update-gfs-of-class class)
+  (update-inits class (compute-default-initargs class))
+  (update-make-instance-function-table class))
+
+(defmethod finalize-inheritance ((class forward-referenced-class))
+  (error "~A can't be finalized" class))
+
+(defun update-class (class &optional finalizep)  
+  (declare (ignore finalizep))
+  (unless (class-has-a-forward-referenced-superclass-p class)
+    (finalize-inheritance class)
+    (dolist (sub (class-direct-subclasses class))
+      (update-class sub))))
+