From: Clinton Ebadi <clinton@unknownlamer.org>
Date: Mon, 30 Aug 2010 20:57:49 +0000 (-0400)
Subject: makunbound when +unbound-slot+ is passed to default setter for slot attributes
X-Git-Url: https://git.hcoop.net/clinton/lisp-on-lines.git/commitdiff_plain/c5cd7a181a2c1204b736ceb0bfebd1a2f55e61f4

makunbound when +unbound-slot+ is passed to default setter for slot attributes
* Any custom setters on a CLOS slot will need to implement this behavior
---

diff --git a/src/standard-descriptions/clos.lisp b/src/standard-descriptions/clos.lisp
index 377380d..f1465a1 100644
--- a/src/standard-descriptions/clos.lisp
+++ b/src/standard-descriptions/clos.lisp
@@ -49,7 +49,9 @@
       (unless (attribute-setter object)
 	(setf (attribute-setter object) 
 	      (lambda (v o)
-		(setf (slot-value o (attribute-slot-name object)) v)))))))
+		(if (unbound-slot-value-p v)
+		    (slot-makunbound o (attribute-slot-name object))
+		    (setf (slot-value o (attribute-slot-name object)) v))))))))
 		  
 
 (define-layered-method attribute-value-using-object (object (attribute slot-definition-attribute))