(save-interprogram-paste-before-kill): New user option.

(kill-new): When `save-interprogram-paste-before-kill' is non-nil,
save the interprogram-paste into kill-ring before overriding it
with the Emacs kill.

2 files changed, 30 insertions, 0 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index f3ab3384170..d35097f74a1 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2009-08-26  Sam Steingold  <sds@gnu.org>
+
+	* simple.el (save-interprogram-paste-before-kill): New user option.
+	(kill-new): When `save-interprogram-paste-before-kill' is non-nil,
+	save the interprogram-paste into kill-ring before overriding it
+	with the Emacs kill.
+
 2009-08-26  Dan Nicolaescu  <dann@ics.uci.edu>
 
 	* vc.el (vc-trunk-p): Rename to vc-rcs-trunk-p and move to vc-rcs.el.
diff --git a/lisp/simple.el b/lisp/simple.el
index 7349f4d0617..88cc61a835b 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -2794,6 +2794,17 @@ ring directly.")
 (defvar kill-ring-yank-pointer nil
   "The tail of the kill ring whose car is the last thing yanked.")
 
+(defcustom save-interprogram-paste-before-kill nil
+  "Save the paste strings into `kill-ring' before replacing it with emacs strings.
+When one selects something in another program to paste it into Emacs,
+but kills something in Emacs before actually pasting it,
+this selection is gone unless this variable is non-nil,
+in which case the other program's selection is saved in the `kill-ring'
+before the Emacs kill and one can still paste it using \\[yank] \\[yank-pop]."
+  :type 'boolean
+  :group 'killing
+  :version "23.2")
+
 (defun kill-new (string &optional replace yank-handler)
   "Make STRING the latest kill in the kill ring.
 Set `kill-ring-yank-pointer' to point to it.
@@ -2806,6 +2817,10 @@ inserted into a buffer; see `insert-for-yank' for details.
 When a yank handler is specified, STRING must be non-empty (the yank
 handler, if non-nil, is stored as a `yank-handler' text property on STRING).
 
+When `save-interprogram-paste-before-kill' and `interprogram-paste-function'
+are non-nil, saves the interprogram paste string(s) into `kill-ring' before
+STRING.
+
 When the yank handler has a non-nil PARAM element, the original STRING
 argument is not used by `insert-for-yank'.  However, since Lisp code
 may access and use elements from the kill ring directly, the STRING
@@ -2819,6 +2834,14 @@ argument should still be a \"useful\" string for such uses."
 		(list string "yank-handler specified for empty string"))))
   (if (fboundp 'menu-bar-update-yank-menu)
       (menu-bar-update-yank-menu string (and replace (car kill-ring))))
+  (when save-interprogram-paste-before-kill
+    (let ((interprogram-paste (and interprogram-paste-function
+                                   (funcall interprogram-paste-function))))
+      (when interprogram-paste
+        (if (listp interprogram-paste)
+            (dolist (s (nreverse interprogram-paste))
+              (push s kill-ring))
+            (push interprogram-paste kill-ring)))))
   (if (and replace kill-ring)
       (setcar kill-ring string)
     (push string kill-ring)