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

[Richard M. Stallman]

Index: emacs/lisp/subr.el
diff -c emacs/lisp/subr.el:1.277 emacs/lisp/subr.el:1.278
*** emacs/lisp/subr.el:1.277    Tue Dec 11 02:34:39 2001
--- emacs/lisp/subr.el  Wed Dec 12 04:26:43 2001
***************
*** 1294,1299 ****
--- 1294,1309 ----
       (let ((delay-mode-hooks t))
         ,@body)))
  
+ ;; PUBLIC: find if the current mode derives from another.
+ 
+ (defun derived-mode-p (&rest modes)
+   "Non-nil if the current major mode is derived from one of MODES.
+ Uses the `derived-mode-parent' property of the symbol to trace backwards."
+   (let ((parent major-mode))
+     (while (and (not (memq parent modes))
+               (setq parent (get parent 'derived-mode-parent))))
+     parent))
+ 
  (defmacro with-syntax-table (table &rest body)
    "Evaluate BODY with syntax table of current buffer set to a copy of TABLE.
  The syntax table of the current buffer is saved, BODY is evaluated, and the