+(define-layered-class slot-definition-attribute (standard-attribute)
+ ((slot-name :initarg :slot-name
+ :accessor attribute-slot-name
+ :layered t)))
+
+(defmethod shared-initialize :around ((object slot-definition-attribute)
+ slots &rest args)
+ (prog1 (call-next-method)
+ (unless (attribute-setter object)
+ (setf (attribute-setter object)
+ (lambda (v o)
+ (setf (slot-value o (attribute-slot-name object)) v))))))
+
+
+(define-layered-method attribute-value-using-object (object (attribute slot-definition-attribute))
+ (if (slot-boundp object (attribute-slot-name attribute))
+
+ (slot-value object (attribute-slot-name attribute))
+ +unbound-slot+))
+
+(defun ensure-description-for-class (class &optional (name (intern (format nil "DESCRIPTION-FOR-~A" (class-name class)))))
+ (let ((desc-class
+ (ensure-class (defining-description name)
+ :direct-superclasses (list (class-of (find-description 'standard-object)))
+ :direct-slots (loop :for slot in (class-slots class)
+ :collect `(:name ,(slot-definition-name slot)
+ :attribute-class slot-definition-attribute
+ :slot-name ,(slot-definition-name slot)
+ :label ,(format nil
+ "~@(~A~)" (substitute #\Space #\- (symbol-name (slot-definition-name slot)))))
+ :into slots
+ :collect (slot-definition-name slot) :into names
+ :finally (return (cons `(:name active-attributes
+ :value ',names)
+ slots)))
+ :metaclass 'standard-description-class)))
+
+ (unless (ignore-errors (find-description (class-name class)))
+ (ensure-class (defining-description (class-name class))
+ :direct-superclasses (list desc-class)
+ :metaclass 'standard-description-class))
+ (find-description name)))
+
+
+(defclass described-class ()
+ ())
+
+(defmethod validate-superclass
+ ((class described-class)
+ (superclass standard-class))
+ t)
+
+(defmethod initialize-instance :after ((class described-class) &rest initargs &key (direct-superclasses '()))
+ (declare (dynamic-extent initargs))
+ (finalize-inheritance class)
+ (ensure-description-for-class class))
+
+
+(defmethod reinitialize-instance :after ((class described-class) &rest initargs &key (direct-superclasses '() direct-superclasses-p))
+ (declare (dynamic-extent initargs))
+ (finalize-inheritance class)
+ (ensure-description-for-class class))
+
+(defclass described-standard-class (standard-class described-class) ())
+
+(defmethod validate-superclass
+ ((class described-standard-class)
+ (superclass standard-class))
+ t)
+