Re: (other-window) with negative argument

[Stephen Berman]

On Fri, 21 Dec 2018 17:55:23 +0100 dieter@duenenhof-wilhelm.de (H. Dieter 
Wilhelm) wrote:

> Hello ()
>
> I can't get a function to work with a negative argument of
> (other-window).  When I'm using (other-window -1) in the *scratch*
> buffer it is working as expected, as soon as I put it into a function
> like the following
>
> (defun previous-window ()
>   (other-window -1))
>
> or 
>
> (defun previous-window ()
>   "blabla"
>   (interactive)
>   (other-window -1))
>
> and activate the function any call to (other-window -1) is opening the
> debugger!
>
> What am I doing wrong?

Redefining a function, previous-window, which is a primitive Emacs
function defined in C.  When other-window has a negative argument, it
calls the built-in previous-window with three arguments, which are
optional in the built-in version, and since your redefinition takes no
arguments, this raises the error.  If you name your function
e.g. my-previous-window, it will work as you expect.

Steve Berman