>
Thanks for the patch. It would be nice to have such commands
>
even not bound to default keys, so the users are free to bind
> them to any keys.
That's my hope, unless sufficiently good default keys can be found. I like C-M-space and C-M-S-space, which are both currently bound to mark-sexp, but changing the default keys is not trivially done.
> So looks like the best place to define the helper is simple.el,
> before mark-word.
Sure! I'll get a patch out for this.
> Another variant is to use a single argument JUMPFORM like
> in 'isearch-yank-internal' that allows not to leak the
> prefix argument to the helper function:
This is tempting. The downside I'm seeing to this -- which I'll think more about to see if I can get around it -- is that we don't know if we need to call JUMPFORM from point or mark.
We can do it from both, something like:
(defun mark--helper (fn-to-find-new-mark)
"Extend region by calling FN-TO-FIND-NEW-MARK.
The MOVE-FN should take a numeric argument, and move that many
items forward (negative means backward).
NUMBER-OF-THINGS is the number of additional things to move."
(if (use-region-p)
(let* ((beginning-of-region (region-beginning))
(end-of-region (region-end))
(at-end-of-region (= end-of-region (point)))
(move-from-front (save-excursion (goto-char beginning-of-region)
(funcall fn-to-find-new-mark)
(point)))
(move-from-end (save-excursion (goto-char end-of-region)
(funcall fn-to-find-new-mark)
(point)))
(new-beginning-of-region (min beginning-of-region move-from-front))
(new-end-of-region (max end-of-region move-from-end)))
(goto-char (if at-end-of-region
new-end-of-region
new-beginning-of-region))
(set-mark (if at-end-of-region
new-beginning-of-region
new-end-of-region)))
(progn (push-mark (save-excursion
(funcall fn-to-find-new-mark)
(point)))
(activate-mark))))
Downsides include:
1. We have to call the function twice each time. This doesn't seem like such a big deal unless it's expensive or has side effects -- neither of which should be the case.
2. The current implementation errors when there are no more objects to mark. This doesn't. I think we probably could error if we don't change the region.
3. I'm not 100% convinced this will always do the right thing. I would like to be.
4. I'm not sure going to one argument is worth it. The two arguments seem pretty simple; changing to one argument might add more complexity than it removes.