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

diff --git a/src/description.lisp b/src/description.lisp
index 710771f..2ce2c81 100644
--- a/src/description.lisp
+++ b/src/description.lisp
@@ -1,5 +1,8 @@
 (in-package :lisp-on-lines)
 
+(defvar *object* nil)
+(defvar *description*)
+
 (define-layered-function description-of (thing)
   (:method (thing)
     (find-description 't)))
@@ -10,9 +13,25 @@
 (defun description-attributes (description)
   (description-class-attributes (class-of description)))
 
-(defun find-attribute (description attribute-name)
-  (find attribute-name (description-attributes description)
-	:key #'attribute-name))
+(defun description-current-attributes (description)
+  	  (remove-if-not 
+	   (lambda (attribute)
+	     (and 		     
+	      (some #'layer-active-p 
+			(mapcar #'find-layer 
+				(slot-definition-layers 
+				 (attribute-effective-attribute-definition attribute))))))
+	   (description-attributes description)))
+
+(defun description-active-attributes (description)
+  	  (remove-if-not 
+	   #'attribute-active-p
+	   (description-attributes description)))
+
+(defun find-attribute (description attribute-name &optional (errorp t))
+  (or (find attribute-name (description-attributes description)
+	    :key #'attribute-name)
+      (when errorp (error "No attribute named ~A found in ~A describing ~A" attribute-name description (described-object description)))))
 
 (define-layered-function description-active-descriptions (description)
   (:method ((description standard-description-object))
@@ -31,30 +50,59 @@
     (let* ((active-attributes 
 	    (find-attribute description 'active-attributes))
 	   (attributes (when active-attributes
-	     (attribute-value active-attributes))))
-      (if attributes
-	  (mapcar (lambda (spec)		    
-		    (find-attribute 
-		     description
-		     (if (listp spec)
-			 (car spec)
-			 spec)))
-		  attributes)
-	  (remove-if-not 
-	   (lambda (attribute)
-	     (and (attribute-active-p attribute)		     
-		  (some #'layer-active-p 
-			(mapcar #'find-layer 
-				(slot-definition-layers 
-				 (attribute-effective-attribute-definition attribute))))))
+			 (ignore-errors (attribute-value active-attributes)))))
+      (remove-if-not 
+       (lambda (attribute)
+	 (and attribute
+	      (attribute-active-p attribute)		     
+	      (some #'layer-active-p 
+		    (mapcar #'find-layer 
+			    (slot-definition-layers 
+			     (attribute-effective-attribute-definition attribute))))))
+       (if attributes
+	   (mapcar (lambda (spec)		    
+		     (find-attribute 
+		      description
+		      (if (listp spec)
+			  (car spec)
+			  spec)))
+		   attributes)
 	   (description-attributes description))))))
 	  
 
-
-  
-
-  
-;;; A handy macro.
+(defun funcall-with-described-object (function object description &rest args)
+  (setf description (or description (description-of object)))
+  (let ((*description* description)
+	(*object*  object))
+    (dletf (((described-object *description*) object))
+	(funcall-with-layer-context
+	 (modify-layer-context 
+	  (if (standard-description-p *description*)
+	      (adjoin-layer *description* (current-layer-context))
+	      (current-layer-context))
+	  :activate (description-active-descriptions *description*)
+	  :deactivate (description-inactive-descriptions *description*))
+	 (lambda () (contextl::funcall-with-special-initargs  
+		     (loop 
+			:for (key val) :on args :by #'cddr
+			:collect (list (find key (description-attributes *description*) 
+					     :key #'attribute-keyword)
+				       :value val))
+		     (lambda ()
+		       (contextl::funcall-with-special-initargs  
+			(let ((attribute (ignore-errors (find-attribute *description* 'active-attributes))))	
+			  (when attribute
+			    (loop for spec in (attribute-value attribute)
+			       if (listp spec)
+			       collect (cons (or 
+					      (find-attribute *description* (car spec))
+					      (error "No attribute matching ~A" (car spec)))
+					     (cdr spec)))))
+			function))))))))
+
+
+
+		   
 (defmacro define-description (name &optional superdescriptions &body options)
   (let ((description-name (defining-description name)))     
     (destructuring-bind (&optional slots &rest options) options