Re: About `current-kill'

[Xue Fuqiao]

On Mon, 18 Mar 2013 01:38:24 +0100
Stephen Berman <stephen.berman@gmx.net> wrote:

> > In the definition of the function `current-kill':
[...]
> >       (let ((ARGth-kill-element
> >          (nthcdr (mod (- n (length kill-ring-yank-pointer))
> >                       (length kill-ring))
> >                  kill-ring)))
[...]
> > I understand what `ARGth-kill-element' does (from its name).  But how
> > does it work?  I cannot understand it.

> The kill-ring is a list of buffer substrings.  As a ring, you can cycle
> through it

That's what I've forgotten, thanks.  It will be good if the {mark,kill}
ring uses ring.el, I think.

> e.g. if its length is 5, taking its cdr 8 times returns the
> same result as taking its cdr 3 times; that's what the mod function
> guarantees.  So nthcdr skips over the first n elements of the kill-ring,
> and the car of the resulting list becomes the current-kill.

That's true, and `(mod -3 5)' evaluates 2.  It suits this feature exactly.

-- 
Xue Fuqiao
http://www.gnu.org/software/emacs/