[Emacs-diffs] Changes to emacs/lisp/subr.el

[Kim F . Storm]

Index: emacs/lisp/subr.el
diff -c emacs/lisp/subr.el:1.462 emacs/lisp/subr.el:1.463
*** emacs/lisp/subr.el:1.462    Mon Jun 13 20:45:50 2005
--- emacs/lisp/subr.el  Mon Jun 13 21:29:52 2005
***************
*** 957,962 ****
--- 957,988 ----
             (append (symbol-value list-var) (list element))
           (cons element (symbol-value list-var))))))
  
+ 
+ (defun add-to-ordered-list (list-var element &optional order)
+   "Add to the value of LIST-VAR the element ELEMENT if it isn't there yet.
+ The test for presence of ELEMENT is done with `equal'.
+ 
+ The resulting list is reordered so that the elements are in the
+ order given by each element's `list-order' property (a number).
+ Elements which are not symbols, and symbol elements without a
+ numeric `lisp-order' property are placed at the end of the list.
+ 
+ If the third optional argument ORDER is non-nil and ELEMENT is
+ a symbol, set the symbol's `list-order' property to the given value.
+ 
+ The return value is the new value of LIST-VAR."
+   (when (and order (symbolp element))
+     (put element 'list-order (and (numberp order) order)))
+   (add-to-list list-var element)
+   (set list-var (sort (symbol-value list-var)
+                     (lambda (a b)
+                       (let ((oa (and (symbolp a) (get a 'list-order)))
+                             (ob (and (symbolp b) (get b 'list-order))))
+                         (cond
+                          ((not oa) nil)
+                          ((not ob) t)
+                          (t (< oa ob))))))))
+ 
  
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