(delete-selection-pre-hook): Avoid clearing out

pre-command-hook when text is read-only.

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 370f63021b3ec0cac1bf9c0b2b4af922729f0576..34a8222c13faa83e3a9bce27e9feca10c86b5ae3 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2008-01-24  Martin Rudalics  <rudalics@gmx.at>
+
+       * delsel.el (delete-selection-pre-hook): Avoid clearing out
+       pre-command-hook when text is read-only.
+
 2008-01-24  Thien-Thi Nguyen  <ttn@gnuvola.org>
 
        * vc.el (vc-process-filter): Do nothing if buffer not live.

diff --git a/lisp/delsel.el b/lisp/delsel.el
index 6427c39eecb4cd149e03e7ecece06faa58ecbcd2..990ca91ace2375522af8f04cbb31d8986d77d01e 100644 (file)
--- a/lisp/delsel.el
+++ b/lisp/delsel.el
@@ -113,7 +113,23 @@ any selection."
         ;; stop safe_run_hooks from clearing out pre-command-hook.
         (and (eq inhibit-quit 'pre-command-hook)
              (setq inhibit-quit 'delete-selection-dummy))
-        (signal 'file-supersession (cdr data)))))))
+        (signal 'file-supersession (cdr data)))
+       (text-read-only
+        ;; This signal may come either from `delete-active-region' or
+        ;; `self-insert-command' (when `overwrite-mode' is non-nil).
+        ;; To avoid clearing out `pre-command-hook' we handle this case
+        ;; by issuing a simple message.  Note, however, that we do not
+        ;; handle all related problems: When read-only text ends before
+        ;; the end of the region, the latter is not deleted but any
+        ;; subsequent insertion will succeed.  We could avoid this case
+        ;; by doing a (setq this-command 'ignore) here.  This would,
+        ;; however, still not handle the case where read-only text ends
+        ;; precisely where the region starts: In that case the deletion
+        ;; would succeed but the subsequent insertion would fail with a
+        ;; text-read-only error.  To handle that case we would have to
+        ;; investigate text properties at both ends of the region and
+        ;; skip the deletion when inserting text is forbidden there.
+        (message "Text is read-only") (ding))))))
 
 (put 'self-insert-command 'delete-selection t)
 (put 'self-insert-iso 'delete-selection t)