Re: gnus-registry flags API

[Ted Zlatanov <tzz@lifelogs.com>]

On Thu, 28 Feb 2008 21:04:04 +0100 Reiner Steib <reinersteib+gmane@imap.cc> wrote: 

RS> On Thu, Feb 28 2008, Ted Zlatanov wrote:
>> On Sat, 16 Feb 2008 21:26:36 +0100 Reiner Steib <reinersteib+gmane@imap.cc> wrote: 
RS> Can we have multiple registry marks for a single article?  If not, we
RS> may either display all strings/images or add a plus sign.
>> 
>> Yes, multiples are allowed.  That's what makes it tricky to display
>> them, so I haven't done it yet :)
>> 
>> Maybe reserve 4 characters, 

RS> Or just use the number from the format specifier, if feasible.

>> and if more than 4 labels are set, show the first 3 and then '+'.
>> In the modeline or in the article buffer with a post-processing
>> function we can show them all.  I don't know much about this area of
>> Gnus, especially image display, sorry.

RS> Me neither.  But I'd guess we can do it like in
RS> `gnus-mode-line-buffer-identification' (`add-text-properties') or
RS> `gnus-picon-transform-address' (`propertize').

RS> E.g. try this in *scratch* (while running Gnus):

RS> (add-text-properties 4 5
RS> 		     (list 'display gnus-mode-line-image-cache
RS> 			   'help-echo "To do")
RS> 		     (current-buffer))

I couldn't figure out the text properties, or how to update the summary
line as soon as a flag is set.  For now I've comitted a function
gnus-registry-user-format-function-M that shows the flags (unsorted, in
the order they were set).  But the user has to exit the group and
re-enter it to see the new flags.  I'll take a look again but if someone
knows how to do it, please let me know to save me all the work.

Also the string-building construct in that function

(defun gnus-registry-user-format-function-M (headers)
  (let* ((id (mail-header-message-id headers))
	 (marks (when id (gnus-registry-fetch-extra-marks id)))
	 (out ""))
    (dolist (mark marks)
      (let ((c (plist-get
		(cdr-safe
		 (assoc mark gnus-registry-marks)) :char)))
	(setq out (format "%s%s"
			  out
			  (if c
			      (char-to-string c)
			    "")))))
      out))

is ugly.  How would I do the same with mapcar?  I couldn't find a nice
way to eliminate nil entries (when the flag has no :char property) from
the resulting list I would pass to concat; concat would get a list like
(?l ?i nil) and fail.

Ted