bug#11295: 24.0.95; New ibuffer filter derived-mode

[Ivan Andrus]

On Apr 21, 2012, at 4:24 PM, Stefan Monnier wrote:

>> (define-ibuffer-filter derived-mode
>>     "Toggle current view to buffers whose major mode inherits from 
>> QUALIFIER."
>>   (:description "major mode"
>>                 :reader
>>                 (intern
>>                  (completing-read "Filter by major mode: " obarray
>>                                   #'(lambda (e)
>>                                       (string-match "-mode$"
>>                                                     (symbol-name e)))
> 
> This completion table doesn't sound very good.  Much better would be to
> collect all major modes in use and all their parents.

That is a much better idea.  As I said, I just copy/pasted without thinking too 
much.  My main use case is for `ibuffer-saved-filter-groups' so completion 
doesn't matter at all there.

>>                                   t
>>                                   (let ((buf (ibuffer-current-buffer)))
>>                                     (if (and buf (buffer-live-p buf))
>>                                         (symbol-name (buffer-local-value 
>> 'major-mode buf))
>>                                       "")))))
>>   (let ((parent (buffer-local-value 'major-mode buf)))
>>     (while (and (not (eq parent qualifier))
>>                 (setq parent (get parent 'derived-mode-parent))))
>>     (eq parent qualifier)))
> 
> Why not use (with-current-buffer buf (derived-mode-p parent))?

Uh.  That would have been too easy.  :-)

> Another question: couldn't it simply *replace* the existing mode filter?

> I guess it could be a bit annoying if you want to see fundamental-mode
> buffers (since most modes derive from it), but that's the only downside
> I can think of.


I thought about it, but I do in fact filter by fundamental-mode (and a few 
other modes) to hide "useless" buffers.  

-Ivan