X-Git-Url: https://git.hcoop.net/clinton/lisp-on-lines.git/blobdiff_plain/b7657b86f85f575d5776dc6b626b1dc258d1fa47..ec6dde1ef5ec97747c6ebfcc7f35b3d9da75843f:/src/attribute.lisp

diff --git a/src/attribute.lisp b/src/attribute.lisp
index 210b36d..a229aa3 100644
--- a/src/attribute.lisp
+++ b/src/attribute.lisp
@@ -69,7 +69,7 @@
   (attribute-class 
    :accessor attribute-class 
    :initarg :attribute-class 
-   :initform 'standard-attribute)
+  :initform 'standard-attribute)
   (keyword
    :layered-accessor attribute-keyword
    :initarg :keyword
@@ -134,6 +134,12 @@
 		       :layered t
 		       :special t)))
 
+(define-layered-method attribute-active-p :around (attribute)		       
+ (let ((active? (call-next-method)))
+   (if (eq :when active?)
+       (not (null (attribute-value attribute)))
+       active?)))
+		       
 (define-layered-method attribute-label-formatter :around (attribute)
    (or (slot-value attribute 'label-formatter) 
        (attribute-value (find-attribute (attribute-description attribute) 'label-formatter))
@@ -284,7 +290,9 @@
 		(with-function-access 
 		  (slot-value-using-class class attribute property))
 		(funcall fn layer (attribute-description attribute)))
-	    (funcall fn layer (attribute-description attribute))))))
+	    (handler-case (funcall fn layer (attribute-description attribute))
+	      (error ()
+		(warn "Error calling ~A" fn)))))))
 		    
 	      
 
@@ -319,7 +327,7 @@
 (defmacro with-attributes (names description &body body)
   `(let ,(loop for name in names collect 
 	      (list name `(find-attribute ,description ',name)))
-     ,@body))q
+     ,@body))