* lisp/whitespace.el (whitespace-enable-predicate): New variable.

(whitespace-enable-predicate): Use it.

2 files changed, 26 insertions, 21 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 8d2fdc9fcd6..4add4d9383f 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,8 @@
 2013-03-10  Stefan Monnier  <monnier@iro.umontreal.ca>
 
+        * whitespace.el (whitespace-enable-predicate): New variable.
+        (whitespace-enable-predicate): Use it.
+
         * comint.el (comint-send-input, comint-snapshot-last-prompt)
         (comint-output-filter, comint-update-fence):
         Use with-silent-modifications.
diff --git a/lisp/whitespace.el b/lisp/whitespace.el
index ed7edbc5a68..975b89f2fc2 100644
--- a/lisp/whitespace.el
+++ b/lisp/whitespace.el
@@ -1145,29 +1145,31 @@ See also `whitespace-style', `whitespace-newline' and
         (unless whitespace-mode
           (whitespace-turn-off)))))))
 
+(defvar whitespace-enable-predicate
+  (lambda ()
+    (and (cond
+          ((eq whitespace-global-modes t))
+          ((listp whitespace-global-modes)
+           (if (eq (car-safe whitespace-global-modes) 'not)
+               (not (memq major-mode (cdr whitespace-global-modes)))
+             (memq major-mode whitespace-global-modes)))
+          (t nil))
+         ;; ...we have a display (we're running a batch job)
+         (not noninteractive)
+         ;; ...the buffer is not internal (name starts with a space)
+         (not (eq (aref (buffer-name) 0) ?\ ))
+         ;; ...the buffer is not special (name starts with *)
+         (or (not (eq (aref (buffer-name) 0) ?*))
+             ;; except the scratch buffer.
+             (string= (buffer-name) "*scratch*"))))
+  "Predicate to decide which buffers obey `global-whitespace-mode'.
+This function is called with no argument and should return non-nil
+if the current buffer should obey `global-whitespace-mode'.
+This variable is normally modified via `add-function'.")
 
 (defun whitespace-turn-on-if-enabled ()
-  (when (cond
-         ((eq whitespace-global-modes t))
-         ((listp whitespace-global-modes)
-          (if (eq (car-safe whitespace-global-modes) 'not)
-              (not (memq major-mode (cdr whitespace-global-modes)))
-            (memq major-mode whitespace-global-modes)))
-         (t nil))
-    (let (inhibit-quit)
-      ;; Don't turn on whitespace mode if...
-      (or
-       ;; ...we don't have a display (we're running a batch job)
-       noninteractive
-       ;; ...or if the buffer is invisible (name starts with a space)
-       (eq (aref (buffer-name) 0) ?\ )
-       ;; ...or if the buffer is temporary (name starts with *)
-       (and (eq (aref (buffer-name) 0) ?*)
-            ;; except the scratch buffer.
-            (not (string= (buffer-name) "*scratch*")))
-       ;; Otherwise, turn on whitespace mode.
-       (whitespace-turn-on)))))
-
+  (when (funcall whitespace-enable-predicate)
+    (whitespace-turn-on)))
 
 ;;;###autoload
 (define-minor-mode global-whitespace-newline-mode