[PATCH 3/3] Add `notes' function to store random notes across Emacs restarts.

[Michal Nazarewicz]

You may think of it as a *scratch* buffer whose content is preserved.
In fact, it was designed as a replacement for *scratch* buffer and can
be used that way by setting `initial-buffer-choice' to 'notes an
`notes-buffer-name' to "*scratch*".  Without the second
change, *scratch* buffer will still be there for notes that do not
need to be preserved.

* notes.el: New file.
* remember.el (remember-data-file): Added :set callback to affect
notes buffer (if any).
(remember-append-to-file): Fixed buffer visiting a file checking.
Function used `find-buffer-visiting' to check whether such buffer
exists but then `get-buffer-visiting' to retrieve it.  However,
the latter requires exact string match so it could return nil even
though the former found a buffer.
(notes, toggle-notes): New functions for showing the notes buffer.
(notes-file, notes-recover-from-auto-save-file, notes-buffer-name)
(bury-notes-on-kill): New defcustoms for the notes buffer.
(notes--buffer, notes-map): New variables for the `notes' function.
(notes--custom-set-file, notes--insert-content)
(notes--kill-buffer-query): New helper functions.
* startup.el (initial-buffer-choice): Added notes to custom type.
* window.el (save-and-bury-buffer): New function doing what the
name says.
---
 etc/NEWS                   |   8 +++
 lisp/ChangeLog             |  21 +++++++
 lisp/startup.el            |   3 +-
 lisp/textmodes/remember.el | 152 ++++++++++++++++++++++++++++++++++++++++++++-
 lisp/window.el             |   8 +++
 5 files changed, 190 insertions(+), 2 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 475b4b2..ebe6589 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -87,6 +87,14 @@ simply disabling Transient Mark mode does the same thing.
 ** `initial-buffer-choice' can now specify a function to set up the
 initial buffer.
 
+** `notes' function creates a buffer whose content is saved on kill-emacs.
+You may think of it as a *scratch* buffer whose content is preserved.
+In fact, it was designed as a replacement for *scratch* buffer and can
+be used that way by setting `initial-buffer-choice' to 'notes an
+`notes-buffer-name' to "*scratch*".  Without the second
+change, *scratch* buffer will still be there for notes that do not
+need to be preserved.
+
 ** `write-region-inhibit-fsync' now defaults to t in batch mode.
 
 ** ACL support has been added.
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d7a16a6..2a7caf8 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,26 @@
 2013-06-21  Michal Nazarewicz  <address@hidden>
 
+       Add `notes' function to store random notes across Emacs restarts.
+       * notes.el: New file.
+       * remember.el (remember-data-file): Added :set callback to affect
+       notes buffer (if any).
+       (remember-append-to-file): Fixed buffer visiting a file checking.
+       Function used `find-buffer-visiting' to check whether such buffer
+       exists but then `get-buffer-visiting' to retrieve it.  However,
+       the latter requires exact string match so it could return nil even
+       though the former found a buffer.
+       (notes, toggle-notes): New functions for showing the notes buffer.
+       (notes-file, notes-recover-from-auto-save-file, notes-buffer-name)
+       (bury-notes-on-kill): New defcustoms for the notes buffer.
+       (notes--buffer, notes-map): New variables for the `notes' function.
+       (notes--custom-set-file, notes--insert-content)
+       (notes--kill-buffer-query): New helper functions.
+       * startup.el (initial-buffer-choice): Added notes to custom type.
+       * window.el (save-and-bury-buffer): New function doing what the
+       name says.
+
+2013-06-19  Michal Nazarewicz  <address@hidden>
+
        * remember.el (remember-append-to-file): Function used
        `find-buffer-visiting' to check whether a file visiting
        `remember-data-file` existed but then `get-buffer-visiting' to
diff --git a/lisp/startup.el b/lisp/startup.el
index 77b2bce..7004015 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -53,7 +53,8 @@ or directory when no target file is specified."
          (const     :tag "Startup screen" nil)
          (directory :tag "Directory" :value "~/")
          (file      :tag "File" :value "~/.emacs")
-          (function  :tag "Function")
+         (const     :tag "Notes buffer" notes)
+         (function  :tag "Function")
          (const     :tag "Lisp scratch buffer" t))
   :version "24.4"
   :group 'initialization)
diff --git a/lisp/textmodes/remember.el b/lisp/textmodes/remember.el
index a14a34c..6b106c7 100644
--- a/lisp/textmodes/remember.el
+++ b/lisp/textmodes/remember.el
@@ -382,8 +382,12 @@ Subject: %s\n\n"
 ;; Remembering to plain files
 
 (defcustom remember-data-file (locate-user-emacs-file "notes" ".notes")
-  "The file in which to store unprocessed data."
+  "The file in which to store unprocessed data.
+When set via customize, visited file of the notes buffer (if it exists)
+might be changed.  This is only of importance if you are using `notes'."
   :type 'file
+  :set 'notes--custom-set-file
+  :initialize 'custom-initialize-default
   :group 'remember)
 
 (defcustom remember-leader-text "** "
@@ -554,4 +558,150 @@ the data away for latter retrieval, and possible indexing.
 \\{remember-mode-map}"
   (set-keymap-parent remember-mode-map nil))
 
+;; Notes buffer showing the notes:
+
+(defvar notes--buffer nil
+  "The notes buffer.")
+
+(defcustom notes-file t
+  "File to save notes in or t to use `remember-data-file'.
+When set via customize, visited file of the notes buffer \(if it exists)
+will be changed."
+  :type '(choice (const "Same as `remember-data-file'" t)
+                 (file  "Filename"))
+  :set 'notes--custom-set-file
+  :initialize 'custom-initialize-default
+  :group 'remember)
+
+(defcustom notes-recover-from-auto-save-file 'ask
+  "What to do if notes autosave file is newer than the notes file.
+
+t means to always recover content from auto-save file, 'ask means
+to ask user, and nil means never to recover auto-save file (which
+also disables `auto-save-mode' in the notes buffer.
+
+When set via customize, `auto-save-mode' will be enabled or disabled
+in the notes buffer according to this variable's value."
+  :type '(choice (const :tag "Always recover auto-save" t)
+                 (const :tag "Never recover auto-save" nil)
+                 (const :tag "Ask whether to recover auto-save" ask))
+  :set (lambda (symbol value)
+        (set-default symbol value)
+        (when (buffer-live-p notes--buffer)
+          (with-current-buffer notes--buffer
+            (auto-save-mode (if value 1 -1)))))
+  :group 'remember)
+
+(defcustom notes-buffer-name "*notes*"
+  "Name of the notes buffer.
+Setting it to *scratch* will hijack the *scratch* buffer for the
+purpose of storing notes."
+  :type 'string
+  :group 'remember)
+
+(defcustom initial-notes-major-mode t
+  "Major mode to set to notes buffer when it's created.
+If set to t will use the same mode as `initial-major-mode'."
+  :type '(choice (const    :tag "Same as `initial-major-mode'" t)
+                (function :tag "Major mode" text-mode))
+  :group 'remember)
+
+(defcustom bury-notes-on-kill t
+  "Whether to bury notes buffer instead of killing."
+  :type 'boolean
+  :group 'remember)
+
+(defvar notes-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map "\C-c\C-c" 'save-and-bury-buffer)
+    map))
+
+(defun notes--custom-set-file (symbol value)
+  (set-default symbol value)
+  (when (buffer-live-p notes--buffer)
+    (with-current-buffer notes--buffer
+      (setq buffer-file-name
+           (expand-file-name
+            (if (eq notes-file t) remember-data-file notes-file))))))
+
+;;;###autoload
+(defun notes ()
+  "Creates notes buffer and switches to it if called interactively.
+
+Name of the created buffer is taken from `notes-buffer-name' variable
+and if a buffer with that name already exist (but was not created by
+`notes' function), its content will be overwritten.
+\\<notes-map>
+`notes-map' is active in the notes buffer which by default contains
+only one \\[save-and-bury-buffer] binding which saves and buries the buffer.
+
+Function returns notes buffer.
+
+Notes buffer is meant for keeping random notes which you'd like to
+preserve across Emacs restarts.  The notes will be stored in the
+`notes-file'."
+  (interactive)
+  (unless (buffer-live-p notes--buffer)
+    (setq notes--buffer (get-buffer-create notes-buffer-name))
+    (with-current-buffer notes--buffer
+      (funcall (if (eq initial-notes-major-mode t)
+                  initial-major-mode
+                initial-notes-major-mode))
+      (setq buffer-file-name
+           (if (eq notes-file t) remember-data-file notes-file))
+      (setq buffer-save-without-query t)
+      (auto-save-mode (if notes-recover-from-auto-save-file 1 -1))
+      (add-hook 'kill-buffer-query-functions 'notes--kill-buffer-query)
+      (setq minor-mode-overriding-map-alist
+           (cons (cons 'notes--buffer notes-map)
+                 minor-mode-overriding-map-alist))
+      (notes--insert-content)))
+  (when (called-interactively-p 'all)
+    (switch-to-buffer notes--buffer))
+  notes--buffer)
+
+;;;###autoload
+(defun toggle-notes ()
+  "Switches to notes buffer unless already there in which case buries it."
+  (interactive)
+  (if (eq (current-buffer) notes--buffer)
+      (bury-buffer)
+    (switch-to-buffer (notes))))
+
+(defun notes--insert-content ()
+  (let* ((have-file (file-readable-p buffer-file-name))
+        (have-auto-save (and buffer-auto-save-file-name
+                             (file-readable-p buffer-auto-save-file-name))))
+    ;; If autosave is older, pretend it does not exist.
+    (and have-file
+        have-auto-save
+        (not (file-newer-than-file-p buffer-auto-save-file-name
+                                      buffer-file-name))
+        (setq have-auto-save nil))
+    ;; If user wants us to always recover, pretend there's no base file.
+    (and have-auto-save
+        (eq t notes-recover-from-auto-save-file)
+        (setq have-file nil))
+    ;; Ask user what to do.
+    (and have-file
+        have-auto-save
+        (if (y-or-n-p "Recover notes file? ")
+            (setq have-file nil)
+          (setq have-auto-save nil)))
+    (let ((file (cond (have-file buffer-file-name)
+                     (have-auto-save buffer-auto-save-file-name))))
+      (when file
+       (insert-file-contents file nil nil nil t)
+       (goto-char (point-min))
+       (set-buffer-modified-p nil)))))
+
+(defun notes--kill-buffer-query ()
+  (if (not (eq (current-buffer) notes--buffer))
+      t
+    (when (buffer-modified-p)
+      (save-buffer))
+    (if bury-notes-on-kill
+       (bury-buffer)
+      t)))
+
 ;;; remember.el ends here
diff --git a/lisp/window.el b/lisp/window.el
index 5b00198..7eda7ea 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -3429,6 +3429,14 @@ displayed there."
     ;; Always return nil.
     nil))
 
+(defun save-and-bury-buffer ()
+  "Saves and buries current buffer.
+Buffer is saved only if `buffer-modified-p' returns non-nil."
+  (interactive)
+  (when (buffer-modified-p)
+    (save-buffer))
+  (bury-buffer))
+
 (defun unbury-buffer ()
   "Switch to the last buffer in the buffer list."
   (interactive)
-- 
1.8.3.1