X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/b2983f3591981a916f748362d91ff0e2817552cb..e046c3f65a8f7241889fb9b6005aac21e2aad1a8:/src/class-finalize-impl.lisp

diff --git a/src/class-finalize-impl.lisp b/src/class-finalize-impl.lisp
index be42f13..aea5058 100644
--- a/src/class-finalize-impl.lisp
+++ b/src/class-finalize-impl.lisp
@@ -48,6 +48,22 @@
 ;; Superclass Linearization for Dylan' for more detail.
 ;; http://www.webcom.com/haahr/dylan/linearization-oopsla96.html
 
+;;; Utilities.
+
+(export 'merge-class-lists)
+(defun merge-class-lists (lists pick)
+  "Merge the LISTS of classes, using PICK to break ties.
+
+   This is a convenience wrapper around the main `merge-lists' function.
+   Given that class linearizations (almost?) always specify a custom
+   tiebreaker function, this isn't a keyword argument.  Also, this wrapper
+   provides a standard presentation function so that any errors are presented
+   properly."
+  (merge-lists lists
+	       :pick pick
+	       :present (lambda (class)
+			  (format nil "`~A'" (sod-class-name class)))))
+
 ;;; Tiebreaker functions.
 
 (defun clos-tiebreaker (candidates so-far)
@@ -67,7 +83,7 @@
 	(when (member candidate (sod-class-direct-superclasses class))
 	  (setf winner candidate))))
     (unless winner
-      (error "SOD INTERNAL ERROR: Failed to break tie in CLOS."))
+      (error "SOD INTERNAL ERROR: Failed to break tie in CLOS"))
     winner))
 
 (defun c3-tiebreaker (candidates cpls)
@@ -96,7 +112,7 @@
     (dolist (candidate candidates)
       (when (member candidate cpl)
 	(return-from c3-tiebreaker candidate))))
-  (error "SOD INTERNAL ERROR: Failed to break tie in C3."))
+  (error "SOD INTERNAL ERROR: Failed to break tie in C3"))
 
 ;;; Linearization functions.
 
@@ -117,11 +133,11 @@
 	       (remove-duplicates (cons class
 					(mappend #'superclasses
 						 direct-supers))))))
-    (merge-lists (mapcar (lambda (class)
-			   (cons class
-				 (sod-class-direct-superclasses class)))
-			 (superclasses class))
-		 :pick #'clos-tiebreaker)))
+    (merge-class-lists
+     (mapcar (lambda (class)
+	       (cons class (sod-class-direct-superclasses class)))
+	     (superclasses class))
+     #'clos-tiebreaker)))
 
 (export 'dylan-cpl)
 (defun dylan-cpl (class)
@@ -143,9 +159,10 @@
    you're going to lose anyway."
 
   (let ((direct-supers (sod-class-direct-superclasses class)))
-    (merge-lists (cons (cons class direct-supers)
-		       (mapcar #'sod-class-precedence-list direct-supers))
-		 :pick #'clos-tiebreaker)))
+    (merge-class-lists
+     (cons (cons class direct-supers)
+	   (mapcar #'sod-class-precedence-list direct-supers))
+     #'clos-tiebreaker)))
 
 (export 'c3-cpl)
 (defun c3-cpl (class)
@@ -162,8 +179,8 @@
 
   (let* ((direct-supers (sod-class-direct-superclasses class))
 	 (cpls (mapcar #'sod-class-precedence-list direct-supers)))
-    (merge-lists (cons (cons class direct-supers) cpls)
-		 :pick (lambda (candidates so-far)
+    (merge-class-lists (cons (cons class direct-supers) cpls)
+		       (lambda (candidates so-far)
 			 (declare (ignore so-far))
 			 (c3-tiebreaker candidates cpls)))))
 
@@ -224,13 +241,14 @@
    precedence order i.e., the direct-superclasses list orderings."
 
   (let ((dfs (flavors-cpl class)))
-    (cons class (merge-lists (mapcar #'sod-class-precedence-list
+    (cons class
+	  (merge-class-lists (mapcar #'sod-class-precedence-list
 				     (sod-class-direct-superclasses class))
-			     :pick (lambda (candidates so-far)
-				     (declare (ignore so-far))
-				     (dolist (class dfs)
-				       (when (member class candidates)
-					 (return class))))))))
+			     (lambda (candidates so-far)
+			       (declare (ignore so-far))
+			       (dolist (class dfs)
+				 (when (member class candidates)
+				   (return class))))))))
 
 ;;; Default function.
 
@@ -283,7 +301,7 @@
   (reduce (lambda (best this)
 	    (cond ((funcall order best this) best)
 		  ((funcall order this best) this)
-		  (t (error "Unable to choose best ~A." what))))
+		  (t (error "Unable to choose best ~A" what))))
 	  items))
 
 (defmethod guess-metaclass ((class sod-class))