[PATCH] View Differences before saving

[PATCH] View Differences before saving

[Mario Lang]

Hello Emacsers :)

I've just received the confirmation that my
past and future changes assigment arrived
at the FSF.  So I prepared a slightly
improved version of my previos patch (thanks Kim)
for submittion.  I don't have CVS access, so if
the patch looks OK and is accepted that way, I'd like
to ask someone with CVS access to install it.

Here's the ChangeLog entry:

2002-08-20  Mario Lang  <mlang@debian.org>

            * files.el: (diff-buffer-with-file): New function.
            Intended for save-some-buffers-action-alist, but
            useful in general.
            * (save-some-buffers): Removed static
            data in call to map-y-or-n-p and moved into
            save-some-buffers-action-alist.
            * save-some-buffers-action-alist: New variable.
            Added option `d' using diff-buffer-to-file.
 

And here is the patch:

Index: files.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/files.el,v
retrieving revision 1.601
diff -u -r1.601 files.el
--- files.el	15 Aug 2002 20:08:24 -0000	1.601
+++ files.el	20 Aug 2002 13:15:01 -0000
@@ -2992,17 +2992,64 @@
 		 (rename-file (cdr setmodes) buffer-file-name))))))
     setmodes))
 
+(defun diff-buffer-with-file (&optional buffer)
+  "View the differences between BUFFER and its associated file.
+This requires the external program \"diff\" to be in your `exec-path'."
+  (interactive "bBuffer: ")
+  (setq buffer (get-buffer (or buffer (current-buffer))))
+  (let ((buf-filename (buffer-file-name buffer)))
+    (unless buf-filename
+      (error "Buffer %s has no associated file" buffer))
+    (let ((diff-buf (get-buffer-create "*Buffer-diff*")))
+      (with-current-buffer buffer
+	(save-restriction
+	  (widen)
+	  (if (zerop
+	       (shell-command-on-region (point-min) (point-max)
+		(concat "diff "
+			(when (and (boundp 'ediff-custom-diff-options)
+				   (stringp ediff-custom-diff-options))
+			  ediff-custom-diff-options)
+			" " buf-filename " -") diff-buf))
+	      (message "No differences found")
+	    (progn
+	      (with-current-buffer diff-buf
+		(goto-char (point-min))
+		(if (fboundp 'diff-mode)
+		    (diff-mode)
+		  (fundamental-mode)))
+	      (display-buffer diff-buf))))))
+    nil))
+
+(defvar save-some-buffers-action-alist
+  '((?\C-r
+     (lambda (buf)
+       (view-buffer buf
+		    (lambda (ignore)
+		      (exit-recursive-edit)))
+       (recursive-edit)
+       ;; Return nil to ask about BUF again.
+       nil)
+     "display the current buffer")
+    (?d #'diff-buffer-with-file
+	"Show difference to last saved version"))
+  "ACTION-ALIST argument used in call to `map-y-or-n-p'.")
+
 (defun save-some-buffers (&optional arg pred)
   "Save some modified file-visiting buffers.  Asks user about each one.
-You can answer `y' to save, `n' not to save, or `C-r' to look at the
-buffer in question with `view-buffer' before deciding.
+You can answer `y' to save, `n' not to save, `C-r' to look at the
+buffer in question with `view-buffer' before deciding or `d' to
+view the differences using `diff-buffer-to-file'.
 
 Optional argument (the prefix) non-nil means save all with no questions.
 Optional second argument PRED determines which buffers are considered:
 If PRED is nil, all the file-visiting buffers are considered.
 If PRED is t, then certain non-file buffers will also be considered.
 If PRED is a zero-argument function, it indicates for each buffer whether
-to consider it or not when called with that buffer current."
+to consider it or not when called with that buffer current.
+
+See `save-some-buffers-action-alist' if you want to
+change the additional actions you can take on files."
   (interactive "P")
   (save-window-excursion
     (let* ((queried nil)
@@ -3034,15 +3081,7 @@
 		(save-buffer)))
 	     (buffer-list)
 	     '("buffer" "buffers" "save")
-	     (list (list ?\C-r (lambda (buf)
-				 (view-buffer buf
-					      (function
-					       (lambda (ignore)
-						 (exit-recursive-edit))))
-				 (recursive-edit)
-				 ;; Return nil to ask about BUF again.
-				 nil)
-			 "display the current buffer"))))
+	     save-some-buffers-action-alist))
 	   (abbrevs-done
 	    (and save-abbrevs abbrevs-changed
 		 (progn

-- 
CYa,
  Mario

Re: [PATCH] View Differences before saving

[Richard Stallman]

When Emacs invokes diff, it should use the function `diff' found in
diff.el.  Could you rewrite that way?

Please don't refer to variables from ediff; that isn't clean
here.

Other than that, it seems good.  When you have changed those points,
could you send it again?