mu4e: improve mu4e-contact-rewrite-function

Allow mu4e-contact-rewrite-function to return nil to remove a
contact. Improve documentation.

mu4e/mu4e-utils.el

@@ -626,6 +626,17 @@ process."
       (t (format "\"%s\"" ph)))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+(defsubst mu4e~process-contact (contact)
+  "Process CONTACT, possibly rewriting it, or return nil if
+should be removed."
+  (when mu4e-contact-rewrite-function
+    (setq contact (funcall mu4e-contact-rewrite-function contact)))
+  (when contact
+    (let ((name (plist-get contact :name))
+	   (mail (plist-get contact :mail))) 
+      (unless (and mail (string-match mu4e-compose-complete-ignore-address-regexp mail))
+	(if name (format "%s <%s>" (mu4e~rfc822-quoteit name) mail) mail)))))  
+	
 ;; start and stopping
 (defun mu4e~fill-contacts (contacts)
   "We receive a list of contacts, which each contact of the form
@@ -634,9 +645,14 @@ and fill the list `mu4e~contacts-for-completion' with it, with
 each element looking like
   name <email>
 This is used by the completion function in mu4e-compose."
-  (setq mu4e~contact-list contacts)
+  (setq
+    mu4e~contact-list contacts
+    mu4e~contacts-for-completion nil)
   (let ((lst)
-	 ;; sort by the frequency (descending), then timestamp (descending)
+	 ;; sort by the frequency (ascending), then timestamp (ascending)
+	 ;; note -- this the opposite order we'd want, but the
+	 ;; `push' below reverses the order
+	 
 	 ;; FIXME: sadly, the emacs completion subsystem re-sorts the list
 	 ;; before showing candidates, so this doesn't do anything useful yet.
 	 (contacts (sort contacts
@@ -649,18 +665,8 @@ This is used by the completion function in mu4e-compose."
 			   (< tstamp1 tstamp2)
 			   (< freq1 freq2)))))))
     (dolist (contact contacts)
-      (let* ((contact
-	       (if mu4e-contact-rewrite-function
-		 (funcall mu4e-contact-rewrite-function contact) contact))
-              (name (plist-get contact :name))
-              (mail (plist-get contact :mail)))
-	(when mail
-	  (unless ;; ignore some address ('noreply' etc.)
-	    (and mu4e-compose-complete-ignore-address-regexp
-	      (string-match mu4e-compose-complete-ignore-address-regexp mail))
-	  (add-to-list 'lst
-	    (if name (format "%s <%s>" (mu4e~rfc822-quoteit name) mail) mail))))))
-    (setq mu4e~contacts-for-completion lst)
+      (let ((contact (mu4e~process-contact contact)))
+	(when contact (push contact mu4e~contacts-for-completion))))    
     (mu4e-index-message "Contacts received: %d"
       (length mu4e~contacts-for-completion))))
 

mu4e/mu4e-vars.el

@@ -1,6 +1,6 @@
 ;;; mu4e-vars.el -- part of mu4e, the mu mail user agent
 ;;
-;; Copyright (C) 2011-2013 Dirk-Jan C. Binnema
+;; Copyright (C) 2011-2015 Dirk-Jan C. Binnema
 
 ;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -305,10 +305,17 @@ their canonical counterpart; useful as an example."
       (list :name name :mail mail)))
 
 (defcustom mu4e-contact-rewrite-function nil
-  "Function to be used for when processing contacts and rewrite
-them, for example you may use this for correcting typo's, changed
-names and adapting addresses or names to company policies. As an
-example of this, see `mu4e-contact-identity'."
+  "Either nil or a function to be used for when processing
+contacts and rewrite them or remove them altogether.
+
+If the function receives the contact as a list of the form
+     (:name NAME :mail EMAIL)
+(other properties may be there as well)
+
+The function should return either:
+ - nil: remove this contact
+- a possible rewritten cell (:name NAME :mail EMAIL), or simply return
+the functions parameter."
   :type 'function
   :group 'mu4e-compose)
 

mu4e/mu4e.texi

@@ -2791,23 +2791,31 @@ point. Requires the 'formail' tool from procmail."
 @node Contact functions
 @section Contact functions
 
-It can be useful to rewrite the contact information that @t{mu4e}
-provides, for example to convert them to some standardized format, or
-to fix spelling errors.
+It can sometimes be useful to rewrite the contact information that
+@t{mu4e} provides, for example to convert them to some standardized
+format, or to fix spelling errors. And sometimes, you may want to remove
+certain contacts altogether.
 
-You can do this by setting @code{mu4e-contact-rewrite-function} to
-your function, for example:
+For this, @t{mu4e} provides @code{mu4e-contact-rewrite-function}, which
+passes each contact to a user-provided function, which is expected to
+return either the possibly rewritten contact or @code{nil} to remove the
+contact from the list - note that the latter can also be achieved using
+@code{mu4e-compose-complete-ignore-address-regexp}.
+
+Let's look at an example.
 
 @lisp
 (defun my-rewrite-function (contact)
-   (let* ((name (plist-get contact :name))
-	   (mail (plist-get contact :mail))
-	   (actual-name
-	     (cond
-	       ((string= name "jonh smiht") "John Smith")
-	       ;; other replacements
-	       (t name))))
-     (list :name actual-name :mail mail)))
+  (let ((name (or (plist-get contact :name) ""))
+	 (mail (plist-get contact :mail)))
+    (cond
+      ;; jonh smiht --> John Smith
+      ((string= "jonh smiht" name) (list :name "John Smith" :mail mail)) 
+      ;; remove evilspammer from the contacts list
+      ((string= "evilspammer@@example.com" mail) nil)
+      ;; others stay as the are
+      (t contact))))
+
 (setq mu4e-contact-rewrite-function 'my-rewrite-function)
 @end lisp