windows saved in variables, and `save-selected-window'

windows saved in variables, and `save-selected-window'

[Eric Abrahamsen]

I'm writing a minor mode that does a little bit of window management,
including opening two windows on the current buffer, and keeping track
of the two windows in two variables (the variables should be
buffer-local, but I'm seeing the below behavior with regular defvar).

One of the goals is to have a command that conditionally updates what is
displayed in the "other window". The minimum broken version of the code
is below.

During the set up, the two variables *usually* end up pointing to live
windows (ie, #<window 607 on sdfsdgsgdgsg>). Sometimes one of the
variables ends up pointing at a "dead" window: #<window 607>. Either
way, after the use of `save-selected-window' below, one of the windows
is always dead.

Obviously I'm just doing this wrong altogether -- can anyone tell me the
correct approach?

TIA,
Eric

(defvar window-one nil)
(defvar window-two nil)

(define-minor-mode not-a-mode
  "" nil " windows" nil
  (if (null not-a-mode)
      (setq window-one nil
	    window-two nil)
    (split-window-sensibly)
    (setq window-one (selected-window))
    (other-window 1)
    (setq window-two (selected-window))))

(defun update-other-window ()
  (interactive)
  (save-selected-window
    (select-window window-one)
    (goto-char (/ (point-max) 2))
    (recenter)))

Re: windows saved in variables, and `save-selected-window'

[Michael Heerdegen]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> During the set up, the two variables *usually* end up pointing to live
> windows (ie, #<window 607 on sdfsdgsgdgsg>). Sometimes one of the
> variables ends up pointing at a "dead" window: #<window 607>. Either
> way, after the use of `save-selected-window' below, one of the windows
> is always dead.
>
> Obviously I'm just doing this wrong altogether -- can anyone tell me the
> correct approach?

What does one need to reproduce this?  I evaluated your code and enabled
`note-a-mode', and afterwards

(mapcar #'window-live-p (list window-one window-two))

==> (t t)

Also calling (update-other-window) does not change the result.


Michael.

Re: windows saved in variables, and `save-selected-window'

[Eric Abrahamsen]

Michael Heerdegen <michael_heerdegen@web.de> writes:

> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> During the set up, the two variables *usually* end up pointing to live
>> windows (ie, #<window 607 on sdfsdgsgdgsg>). Sometimes one of the
>> variables ends up pointing at a "dead" window: #<window 607>. Either
>> way, after the use of `save-selected-window' below, one of the windows
>> is always dead.
>>
>> Obviously I'm just doing this wrong altogether -- can anyone tell me the
>> correct approach?
>
> What does one need to reproduce this?  I evaluated your code and enabled
> `note-a-mode', and afterwards
>
> (mapcar #'window-live-p (list window-one window-two))
>
> ==> (t t)
>
> Also calling (update-other-window) does not change the result.

Well damn, after a restart of Emacs I'm no longer seeing the weird
behavior. I can't imagine what I did to get it into that state, but
you're right, it's behaving as expected.

Sorry for the noise, and thanks for testing!

Eric