Re: About `current-kill'

[Stephen Berman]

On Mon, 18 Mar 2013 06:32:42 +0800 Xue Fuqiao <xfq.free@gmail.com> 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, 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.

Steve Berman