Type checking for `define-widget'

[gnu-emacs] / lisp / widget.el

diff --git a/lisp/widget.el b/lisp/widget.el
index e648a575a3532a82f98b7b3352ede941d2960af7..539f91e63a0549bb846e18a419b0ca94e757733f 100644 (file)
--- a/lisp/widget.el
+++ b/lisp/widget.el
@@ -1,6 +1,6 @@
 ;;; widget.el --- a library of user interface components
 ;;
-;; Copyright (C) 1996-1997, 2001-2013 Free Software Foundation, Inc.
+;; Copyright (C) 1996-1997, 2001-2015 Free Software Foundation, Inc.
 ;;
 ;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
 ;; Keywords: help, extensions, faces, hypermedia
@@ -83,6 +83,9 @@ create identical widgets:
 * (apply 'widget-create CLASS ARGS)
 
 The third argument DOC is a documentation string for the widget."
+  ;;
+  (unless (or (null doc) (stringp doc))
+    (error "widget documentation must be `nil' or a string."))
   (put name 'widget-type (cons class args))
   (put name 'widget-documentation (purecopy doc))
   name)