bug#70622: [PATCH] New window parameter 'cursor-type'

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 10 May 2024 10:58:58 +0200
> Cc: 70622@debbugs.gnu.org
> From: martin rudalics <rudalics@gmx.at>
> 
>  >>> +DEFUN ("set-window-cursor-type", Fset_window_cursor_type,
>  >>> +       Sset_window_cursor_type, 2, 2, 0,
>  >>> +       doc: /* Set the `cursor-type' of WINDOW to TYPE.
>  >>> +
>  >>> +This setting takes precedence over the variable `cursor-type', and TYPE
>  >>> +has the same format as the value of that variable.  WINDOW nil means use
>  >>> +the selected window.  */)
>  >>> +  (Lisp_Object window, Lisp_Object type)
>  >>> +{
>  >>> +  struct window *w = decode_live_window (window);
>  >>> +
>  >>> +  wset_cursor_type (w, type);
>  >>
>  >> Shouldn't we validate the value of TYPE before plugging it into the
>  >> window?  I know we will validate it at display time, but maybe it's a
>  >> good idea to do that here as well, and signal an error up front?
>  >
>  > AFAICT there are no invalid values, since we take "any other value" to
>  > mean the same as 'hollow' (see C-h v cursor-type), so I think not
>  > validating anything should be perfectly valid :)
>  >
>  >> Martin, WDYT?
> 
> I think Eshel is right.

Any reasons?

>  > Maybe, but that's a bit tricky because we need to consider whether or
>  > not the window is selected and what cursor-in-non-selected-windows has
>  > to say to figure out what the cursor will actually look like.  Currently
>  > this function just provides Lisp with access to the window slot, so we
>  > have all the needed information available in Lisp.  I suggest keeping
>  > 'window-cursor-type' simple and, if the need arises, providing a Lisp
>  > function that calculates the effective cursor type for a given window.
>  > WDYT?
> 
> If needed, the function can be given a second argument that allows to
> retrieve either the value specified for this window or the effective
> value used.

SGTM, thanks.