Re: ruler support in hexl mode

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Based on Stefan and Kim's suggestions, I have revised the patch.
> I've moved the essential functions(`scroll-bar-columns' and `fringe-columns')
> in ruler-mode.el to frame.el and fringe.el and use new functions in
> ruler-mode.el and hexl.el.

Comments:

> +(defcustom hexl-use-ruler t
> +  "If non-nil then show the ruler for hexl mode."
> +  :type 'boolean
> +  :group 'hexl)

I'd call it hexl-use-header-line, but maybe that's just me.

> +(defface hexl-ascii-overlay
> +  ;; Definition borrowed from vcursor.el.
> +  '((((class color)) (:foreground "blue" :background "cyan" :underline t))
> +    (t (:inverse-video t :underline t)))
> +  "Face for the overlay in ascii area of hexl mode buffer."
> +  :group 'hexl)

I'd call it `hexl-ascii-cursor' since the user might not know it's an
overlay (and it could actually be implemented as a text-property tomorrow).
Also I'd stick to just `:inverse-video' as much as possible or more
specifically I'd try to make it look just like the normal cursor (since
there's conceptually no difference between the two).

> +(defcustom hexl-follow-line t
> +  "If non-nil then turn `hl-line-mode' on."
> +  :type 'boolean
> +  :group 'hexl)
[...]
> +    (if hexl-follow-line  (hexl-follow-line 1)))
>    (run-hooks 'hexl-mode-hook))
[...]
> +(defun hexl-follow-line (&optional arg)
> +  "Toggle following line address in Hexl buffers.
> +With prefix ARG, turn on following if and only if ARG is positive.
> +When following is enabled, the line address corresponding to the
> +element under the point is highlighted.
> +Customize the variable `hexl-follow-line' to disable this feature."
> +  (interactive "P")
> +  (let ((on-p (if arg
> +		  (> (prefix-numeric-value arg) 0)
> +		(not hexl-follow-line))))
> +
> +    (setq hexl-follow-line on-p)
> +    (hl-line-mode (if on-p 1 -1))))

You could define this with `define-minor-mode'.
But I'd recommend to go even further and replace the above with:

(defcustom hexl-mode-hook ()
  "Blabla"
  :type 'hook
  :options '(hexl-follow-line))

(defun hexl-follow-line ()
  (hl-line-mode 1))


-- Stefan