+;; defines a slot-unbound method for class and slot-name, fills
+;; the slot by calling reader function with the slot values of
+;; the instance's reader-keys
+(defmacro def-lazy-reader (class slot-name reader &rest reader-keys)
+ (let* ((the-slot-name (gensym))
+ (the-class (gensym))
+ (the-instance (gensym))
+ (keys '()))
+ (dolist (key reader-keys)
+ (push (list 'slot-value the-instance (list 'quote key)) keys))
+ (setq keys (nreverse keys))
+ `(defmethod slot-unbound (,the-class (,the-instance ,class)
+ (,the-slot-name (eql ',slot-name)))
+ (declare (ignore ,the-class))
+ (setf (slot-value ,the-instance ,the-slot-name) (,reader ,@keys)))))
+
+
+#+lispworks
+(defun intern-eql-specializer (slot)
+ `(eql ,slot))
+
+#+(or sbcl cmu lispworks)
+(defun ensure-lazy-reader (class-name slot-name reader &rest reader-keys)
+ (let ((keys nil)
+ (gf (ensure-generic-function 'slot-unbound)))
+ (dolist (key reader-keys)
+ (push (list 'slot-value 'the-instance (list 'quote key)) keys))
+ (setq keys (nreverse keys))
+ (multiple-value-bind (method-lambda init-args-values)
+ (make-method-lambda
+ gf
+ (class-prototype (generic-function-method-class gf))
+ #-lispworks
+ `(lambda (the-class the-instance the-slot-name)
+ (declare (ignore the-class))
+ (setf (slot-value the-instance the-slot-name) (,reader ,@keys)))
+ #+lispworks
+ '(the-class the-instance the-slot-name)
+ #+lispworks
+ nil
+ #+lispworks
+ `(setf (slot-value the-instance the-slot-name) (,reader ,@keys))
+ nil)
+ (add-method gf
+ (apply
+ #'make-instance (generic-function-method-class gf)
+ ':specializers (list (class-of (find-class class-name))
+ (find-class class-name)
+ (intern-eql-specializer slot-name))
+ ':lambda-list '(the-class the-instance the-slot-name)
+ ':function (compile nil method-lambda)
+ init-args-values)))))
+
+(defun finalize-subobjects (cl)