Re: Shorter/customized group names?

[David Engster <deng@randomsample.de>]

David Abrahams <dave@boostpro.com> writes:
> on Fri May 29 2009, David Abrahams <dave-AT-boostpro.com> wrote:
>
>> on Fri May 29 2009, David Engster <deng-AT-randomsample.de> wrote:
>>
>>> David Abrahams <dave@boostpro.com> writes:
>>>> This is pretty cool, but it's also got a few problems.  It relies on
>>>> implementation details of Gnus like the order in which groups get
>>>> formatted, that Gnus always formats *all* the groups (it doesn't) and on
>>>> some secret variables.
>>>
>>> It's a hack, for sure. Maybe the reason it works pretty well for me is
>>> because I'm using topic mode?
>>
>> I'm using topic mode too.
>
> A possibly-less-hacky approach might be to "after" advise the functions
> that operate on the *Group* buffer to postprocess those strings.  Still,
> I really think this (or the tools to support it) should be a built-in
> feature.

I couldn't exactly reproduce the problems you had, but I also noticed
some inconsistencies when the Group buffer is rebuild only partially
(e.g. when opening a topic). I agree that doing this as a postprocess is
the best way to go about this. Since there are more than enough hooks we
don't even need to advise anything. :-)

So here's yet another version, based on your already modified one. It
also uses an internal feature: the complete group name is saved in the
text properties at the beginning of each group line. Since many internal
Gnus functions use these, this isn't likely to change.

--8<---------------cut here---------------start------------->8---
(defun DE-collapse-group-names ()
  (save-excursion
    (let (previous-group current-group common-prefix
			 common-dot-count prefix suffix)
      (goto-char (point-min))
      (while (not (eobp))
	(when (setq current-group 
		    (get-text-property (point) 'gnus-group))
	  (setq current-group (symbol-name current-group))
	  (when (string-match "\\(.+\\):\\(.+\\)" current-group)
	    (setq current-group (match-string 2 current-group)))
	  (setq common-prefix (substring current-group 0 
					 (mismatch previous-group current-group))
		common-dot-count (count ?. common-prefix)
		prefix (mapconcat (lambda (x) x) 
				  (make-list common-dot-count "  .") "")
		suffix (and (string-match
			     (format "\\([^.]*[.]\\)\\{%d\\}\\(.+\\)" common-dot-count) 
			     current-group)
			    (match-string 2 current-group))
		previous-group current-group)
	  (unless (zerop (length prefix))
	    (when (search-forward current-group (point-at-eol) t)
	      (let ((props (text-properties-at (1- (point)))))
		(replace-match (apply 'propertize (concat prefix suffix)
				      props))))))
	(forward-line 1)))))

(add-hook 'gnus-group-prepare-hook 'DE-collapse-group-names)
(add-hook 'gnus-group-update-group-hook 'DE-collapse-group-names)
--8<---------------cut here---------------end--------------->8---

This code assumes that you use "%G" in your group line format.

I think you can even omit the last hook if you don't use a three pane
buffer configuration.

-David