Re: How to get a window Lisp_Object from struct window *w?

Re: How to get a window Lisp_Object from struct window *w?

[Keith David Bershatsky]

Thank you, Eli.  Greatly appreciated!

Keith

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [09-18-2018 01:24:14] <18 Sep 2018 11:24:14 +0300>
> From: Eli Zaretskii <eliz@gnu.org>
> To: Keith David Bershatsky <esq@lawlist.com>
> CC: emacs-devel@gnu.org
> Subject: Re: How to get a window Lisp_Object from struct window *w?
> 
> > Date: Mon, 17 Sep 2018 17:57:45 -0700
> > From: Keith David Bershatsky <esq@lawlist.com>
> >
> > I was wondering if there is a more efficient way to derive window from a struct window *w?
> 
> Like this:
> 
>   struct window *w;
>   Lisp_Object window;
>   XSETWINDOW (window, w);

How to get a window Lisp_Object from struct window *w?

[Keith David Bershatsky]

I am chiseling away at feature requests #17684 (crosshairs) and #22873 (multiple fake cursors).

In this particular example, redisplay gives us the w (struct window *w) as it goes through each window.  I am recording the window Lisp_Object in a cache (also a Lisp_Object) and am later checking that cache to see if w == XWINDOW (window).  There is no guarantee that the window that I am interested in is the selected_window, and the functions giving me the w do not provide the window as an incoming argument.  I see that I can use:

Lisp_Object window = window_from_coordinates (f, opoint_x, opoint_y, &part, true);

get-buffer-window/w->contents is not helpful because there may be more than one window on the frame displaying the same buffer.

I was wondering if there is a more efficient way to derive window from a struct window *w?

Thanks,

Keith

Re: How to get a window Lisp_Object from struct window *w?

[Stefan Monnier]

> I was wondering if there is a more efficient way to derive window from
> a struct window *w?

I'm not sure I understand but if you want the inverse of `XWINDOW`, then
`make_lisp_ptr` will do the trick.

The difference between a `Lisp_Object window` and a `struct window *w`
is just the tag bits which are very cheap&easy to add/remove.


        Stefan

Re: How to get a window Lisp_Object from struct window *w?

[Eli Zaretskii]

> Date: Mon, 17 Sep 2018 17:57:45 -0700
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> I was wondering if there is a more efficient way to derive window from a struct window *w?

Like this:

  struct window *w;
  Lisp_Object window;
  XSETWINDOW (window, w);