Re: follow-up & CC

[Sam Steingold <sds@gnu.org>]

> * Reiner Steib <4.hpr.03.e.f@aheshrefcnz.qr> [2003-11-12 21:00:06 +0100]:
>
> Can `new-header' ever be nil?

no, it is later passed to `insert' which complains about nils.

> BTW, suggestions for a doc-string for
> `message-carefully-insert-headers', anyone?

appended is the new and improved patch.


-- 
Sam Steingold (http://www.podval.org/~sds) running w2k
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--- message.el.~6.380.~	2003-11-10 15:26:08.612774400 -0500
+++ message.el	2003-11-12 16:08:18.618979700 -0500
@@ -2599,15 +2599,34 @@
 		   (message-get-reply-headers t))))
     (message-carefully-insert-headers headers)))
 
+(defvar message-header-synonyms
+  '((To Cc Bcc))
+  "List of lists of header synonyms.
+E.g., if this list contains a member list with elements `Cc' and `To',
+then `message-carefully-insert-headers' will not insert a `To' header
+when the message is already `Cc'ed to the recipient.")
+
 (defun message-carefully-insert-headers (headers)
+  "Insert the headers, an alist, into the message buffer.
+Does not insert the headers when they are already present there
+or in the synonym headers, defined by `message-header-synonyms'."
   (dolist (header headers)
-    (let ((header-name (symbol-name (car header))))
+    (let* ((header-name (symbol-name (car header)))
+           (new-header (cdr header))
+           (synonyms (loop for synonym in message-header-synonyms
+                       when (memq (car header) synonym) return synonym))
+           (old-header
+            (loop for synonym in synonyms
+              for old-header = (mail-fetch-field (symbol-name synonym))
+              when (and old-header (string-match new-header old-header))
+              return synonym)))
+      (if old-header
+          (message "already have `%s' in `%s'" new-header old-header)
       (when (and (message-position-on-field header-name)
-		 (mail-fetch-field header-name)
-		 (not (string-match "\\` *\\'"
-				    (mail-fetch-field header-name))))
+                   (setq old-header (mail-fetch-field header-name))
+                   (not (string-match "\\` *\\'" old-header)))
 	(insert ", "))
-      (insert (cdr header)))))
+        (insert new-header)))))
 
 (defun message-widen-reply ()
   "Widen the reply to include maximum recipients."