bug#65734: [BUG] kill-whole-line on folded subtrees [9.6.8 (release_9.6.8-3-g21171d @ /home/w/usr/emacs/0/29/0/lisp/org/)]

[Ihor Radchenko <yantar92@posteo.net>]

Eli Zaretskii <eliz@gnu.org> writes:

>> > How would kill-line know that it's about to kill a subtree?  All it
>> > knows is that it is killing some invisible text.
>> 
>> I imagine the following:
>> 
>> 1. `kill-*-line' function will, by default, test if invisible text of
>>    length size is killed and query the user when called interactively.
>> 
>> 2. Major modes could also set buffer-local `kill-line-query-function'
>>    that will return nil when killing should proceed without query or a
>>    string with query text.
>
> If the command is only sensitive to invisible text, it could warn
> about so-and-so many invisible characters being killed, but it could
> not warn about "subtrees", which is what you wanted.  Invisible text
> in a buffer could have nothing to do with subtrees, even if the buffer
> is under org-mode.

Let me elaborate. In Elisp, I am thinking about something like:

(defvar-local kill-line-query-function #'kill-line-query-default)
(defun kill-line-query-default (beg end)
  (let ((nlines <count invisible lines between beg end>))
  (when (> nlines threshold)
    (format "Kill %d invisible lines? " nlines))))

Then, Org mode can instead have

(setq-local kill-line-query-function #'org-kill-line-query)
(defun org-kill-line-query (beg end)
  (org-with-point-at beg
    (when (and (org-at-heading-p)
               (progn
                 (end-of-line)
                 (and (< (point) end)
                      (org-fold-folded-p))))
       "Kill hidden subtree along with headline? ")))

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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