git-email: Support appending to header.

Sometimes it is useful to append something to the value of a header
instead of overwriting it.  For example, one might have already Cc’d
someone, but now wants to Cc yet another person, by appending, they
don’t have to re-write the Email address of the first person they
Cc’d.

* git-email.el (git-email--rewrite-header-in-buffer): Add ‘append’
argument.
(git-email-rewrite-header): Add optional prefix argument ‘append’.

Signed-off-by: Xinglu Chen <public@yoctocell.xyz>

1 files changed, 12 insertions, 5 deletions

diff --git a/git-email.el b/git-email.el
index 17e3e0e..485d433 100644
--- a/git-email.el
+++ b/git-email.el
@@ -459,36 +459,43 @@ default behavior is to delete them after sending the message."
             (funcall git-email-send-email-function))
           buffers)))
 
-(defun git-email--rewrite-header-in-buffer (buffer header value)
+(defun git-email--rewrite-header-in-buffer (buffer header value append)
   (switch-to-buffer buffer)
   (save-excursion
     (goto-char (point-min))
     (let* ((case-fold-search t))
       (if (re-search-forward (concat "^" (capitalize header) ":") nil t)
           (progn
-            (delete-region (point) (point-at-eol))
+            (unless append
+              (delete-region (point) (point-at-eol)))
+            (goto-char (point-at-eol))
             (insert " " value))
         (progn
           (re-search-forward "^Subject: .*$")
           (insert "\n" (concat (capitalize header) ": " value)))))))
 
 ;;;###autoload
-(defun git-email-rewrite-header (header value)
+(defun git-email-rewrite-header (header value &optional append)
   "Re-write the value of HEADER to VALUE, if HEADER doesn't exist
 yet, just set it to VALUE.
 
+With prefix argument APPEND, append the VALUE to HEADER instead
+of overwriting it.
+
 This is mainly useful if you forgot to Cc someone when using
 `git-email-format-patch', or if you are waiting for Debbugs to
 give you an address to send your patches to."
   (interactive
    (list (completing-read "Header to re-write: "
                           git-email-headers)
-         (read-from-minibuffer "Set header to: ")))
+         (read-from-minibuffer "Set header to: ")
+         current-prefix-arg))
   (let ((buffers (message-buffers))
         (start-buffer (current-buffer)))
     (save-excursion
        (mapc (lambda (buffer)
-               (git-email--rewrite-header-in-buffer buffer header value))
+               (git-email--rewrite-header-in-buffer
+                buffer header value append))
              buffers))
     (switch-to-buffer start-buffer)))