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;;;; Common Lisp Object System for CLISP
;;;; Objects with stable hash code
;;;; Part 1: Class definition.
;;;; Bruno Haible 2004-05-15
(in-package "CLOS")
;;; ===========================================================================
;;; The class <standard-stablehash> allows CLOS instances to have a
;;; GC-invariant EQ hash code.
;;; Used for (make-hash-table :test 'stablehash-eq).
(defvar *<standard-stablehash>-defclass*
'(defclass standard-stablehash ()
(($hashcode :initform (sys::random-posfixnum))) ; GC invariant hash code
(:fixed-slot-locations t)))
;; Fixed slot locations.
(defconstant *<standard-stablehash>-hashcode-location* 1)
;; No need for accessors. The hashcode is used by hashtabl.d.
;; Initialization of a <standard-stablehash> instance.
(defun shared-initialize-<standard-stablehash> (object situation &rest args
&key &allow-other-keys)
(if *classes-finished*
(apply #'%shared-initialize object situation args) ; == (call-next-method)
; Bootstrapping: Simulate the effect of #'%shared-initialize.
(when (eq situation 't) ; called from initialize-instance?
(setf (standard-instance-access object *<standard-stablehash>-hashcode-location*)
(sys::random-posfixnum))))
object)
;;; ===========================================================================
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