Add a new, simple definition of `remove-duplicates'

2 files changed, 14 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index a3faab15c35..fb2f1a7a6e9 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2011-07-11  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+        * subr.el (remove-duplicates): New conveniency function.
+
 2011-07-10  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
         * tool-bar.el (tool-bar-mode): Clarify positive/negative arguments
diff --git a/lisp/subr.el b/lisp/subr.el
index 5c9d6c8d724..2b7ba17e10c 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -173,7 +173,7 @@ value of last one, or nil if there are none.
     (progn
   ;; If we reload subr.el after having loaded CL, be careful not to
   ;; overwrite CL's extended definition of `dolist', `dotimes',
-  ;; `declare', `push' and `pop'.
+  ;; `declare', `push', `pop' and `remove-duplicates'.
 
 (defmacro dolist (spec &rest body)
   "Loop over a list.
@@ -250,6 +250,15 @@ the return value (nil if RESULT is omitted).
 Treated as a declaration when used at the right place in a
 `defmacro' form.  \(See Info anchor `(elisp)Definition of declare'.)"
   nil)
+
+(defun remove-duplicates (list)
+  "Return a copy of LIST with all duplicate elements removed."
+  (let ((result nil))
+    (while list
+      (unless (member (car list) result)
+        (push (car list) result))
+      (pop list))
+    (nreverse result)))
 ))
 
 (defmacro ignore-errors (&rest body)