Re: find-file-hook, recenter, scroll-conservatively and save-place

[Gergely Risko <gergely@risko.hu>]

On 2019-02-01 10:04 (Friday), martin rudalics <rudalics@gmx.at> writes:
> I have no practice with 'save-place-mode' so I can't tell.  From my
> experience I can only tell that it's disorienting when reverting a
> buffer doesn't preserve window start.

Thanks for catching this, the current proposal toggles the flag in
save-place's hook even on revert-buffer.  Fortunately we have
revert-buffer-in-progress-p, so save-place could do like this:

(defvar-local nce/flagged-for-recenter nil)
(defun nce/flag-for-recenter ()
  (when (not revert-buffer-in-progress-p)
    (setq-local nce/flagged-for-recenter t)))

BTW, my previous fake implementation had some other bugs too :-(

So if anyone is interested here is a better version (still supposed to
be tested with --no-site-file --no-site-lisp --no-splash):
-=-=-=-=-=-
(save-place-mode 1)

(setq vc-follow-symlinks t)
(setq scroll-margin 3)
(setq scroll-conservatively 101)

(defvar-local nce/flagged-for-recenter nil)
(defun nce/flag-for-recenter ()
  (when (not revert-buffer-in-progress-p)
    ;; (message "setting %s %s" (current-buffer) (selected-window))
    (setq-local nce/flagged-for-recenter t)))

(defun nce/recenter-if-flagged (ad-do-it buffer &rest args)
  (let ((window (apply ad-do-it buffer args)))
    (when (buffer-local-value 'nce/flagged-for-recenter buffer)
      (with-selected-window window
	(with-current-buffer buffer
	  ;; (message "unsetting %s" (current-buffer))
	  (setq-local nce/flagged-for-recenter nil)
	  (condition-case nil (recenter) ('error t)))))
    window))

(add-hook 'find-file-hook 'nce/flag-for-recenter)
(advice-add 'display-buffer :around 'nce/recenter-if-flagged)
-=-=-=-=-=-

Martin, I will change save-place to use
`switch-to-buffer-obey-display-actions', as you suggested and will
report back as soon as I have it.

Should I prepare a patch based on these examples, so we have some
existing code to talk about or should we try to come up with something
better than buffer-local variables for passing the info?

Cheers,
Gergely