bug#36361: 'hl-line-range-function' as list of choice

bug#36361: 'hl-line-range-function' as list of choice

[Sebastian Urban]

Because 'hl-line-mode' highlight logical line instead of screen line
when 'visual-line-mode' is active, and for example 'C-a' and 'C-e'
change behaviour, some people want 'hl-line-mode' to change the
behaviour as well.  They usually use 'hl-line-range-function' to
define how it should highlight, but... cannot it be made simpler?
Like by making 'hl-line-range-function' a list of choice:
- nil for default behaviour,
- "Screen line" to change to screen line,
- "Function" for user to write what he wants.
I'm writing this from perspective of "Customize" menu.


S. U.


In GNU Emacs 26.2 (build 1, i686-w64-mingw32)
  of 2019-04-13 built on CIRROCUMULUS
Repository revision: fd1b34bfba8f3f6298df47c8e10b61530426f749
Windowing system distributor 'Microsoft Corp.', version 6.1.7601

bug#36361: 'hl-line-range-function' as list of choice

[Lars Ingebrigtsen]

Sebastian Urban <mrsebastianurban@gmail.com> writes:

> Because 'hl-line-mode' highlight logical line instead of screen line
> when 'visual-line-mode' is active, and for example 'C-a' and 'C-e'
> change behaviour, some people want 'hl-line-mode' to change the
> behaviour as well.  They usually use 'hl-line-range-function' to
> define how it should highlight, but... cannot it be made simpler?
> Like by making 'hl-line-range-function' a list of choice:
> - nil for default behaviour,
> - "Screen line" to change to screen line,
> - "Function" for user to write what he wants.

I think that makes sense, and I think `visual-line-mode' should adjust
`hl-line-range-function' automatically to do the visual line highlight.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#36361: 'hl-line-range-function' as list of choice

[Howard Melman]

FWIW, I've been using the following in Emacs 27.2:

#+begin_src elisp
  (defun visual-line-range-function ()
    "Return a cons cell of positions of begining and end 
  of the current line in `visual-line-mode`. Meant to be used
  as the value of `hl-line-range-function`."
    (save-excursion
      (cons (progn (beginning-of-visual-line) (point))
            (progn (beginning-of-visual-line 2) (point)))))

  (defun set-visual-line-range-function ()
    (setq-local hl-line-range-function
                (if visual-line-mode 'visual-line-range-function nil)))

  (add-hook 'visual-line-mode-hook 'set-visual-line-range-function)
#+end_src

but it seems to conflict with the temporary-goal-column in
line-move-visual.  If I have a buffer:

- foo
- bar
- zot

With point just before foo and do C-n twice, the first one moves point
to just before bar, but the second moves point to the beginning of the
3rd line.

Suggestions for an improved version are welcome.

Howard

bug#36361: 'hl-line-range-function' as list of choice

[Eli Zaretskii]

> From: Howard Melman <hmelman@gmail.com>
> Date: Tue, 26 Oct 2021 14:48:53 -0400
> 
> FWIW, I've been using the following in Emacs 27.2:
> 
> #+begin_src elisp
>   (defun visual-line-range-function ()
>     "Return a cons cell of positions of begining and end 
>   of the current line in `visual-line-mode`. Meant to be used
>   as the value of `hl-line-range-function`."
>     (save-excursion
>       (cons (progn (beginning-of-visual-line) (point))
>             (progn (beginning-of-visual-line 2) (point)))))
> 
>   (defun set-visual-line-range-function ()
>     (setq-local hl-line-range-function
>                 (if visual-line-mode 'visual-line-range-function nil)))
> 
>   (add-hook 'visual-line-mode-hook 'set-visual-line-range-function)
> #+end_src
> 
> but it seems to conflict with the temporary-goal-column in
> line-move-visual.  If I have a buffer:
> 
> - foo
> - bar
> - zot
> 
> With point just before foo and do C-n twice, the first one moves point
> to just before bar, but the second moves point to the beginning of the
> 3rd line.
> 
> Suggestions for an improved version are welcome.

Try this:

  (defun visual-line-range-function ()
    "Return a cons cell of positions of begining and end 
  of the current line in `visual-line-mode`. Meant to be used
  as the value of `hl-line-range-function`."
    (save-excursion
      (cons (progn (vertical-motion 0) (point))
            (progn (vertical-motion 1) (point)))))

bug#36361: 'hl-line-range-function' as list of choice

[Howard Melman]

> On Oct 26, 2021, at 3:11 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> Try this:
> 
>  (defun visual-line-range-function ()
>    "Return a cons cell of positions of begining and end 
>  of the current line in `visual-line-mode`. Meant to be used
>  as the value of `hl-line-range-function`."
>    (save-excursion
>      (cons (progn (vertical-motion 0) (point))
>            (progn (vertical-motion 1) (point)))))

That does seem to work well.  Thanks.

I hope visual-line-mode and hl-line-mode can be made to work 
well together out of the box.

Howard