Re: Emacs Lisp Question

[Thorsten Jolitz <tjolitz@gmail.com>]

drain <aeuster@gmail.com> writes:

> (defun copy-region-as-kill (beg end)
>   "Save the region as if killed, but don't kill it.
>      In Transient Mark mode, deactivate the mark.
>      If `interprogram-cut-function' is non-nil, also save the text for a
> window
>      system cut and paste."
>   (interactive "r")
>   (if (eq last-command 'kill-region)
>       (kill-append (filter-buffer-substring beg end) (< end beg))
>     (kill-new (filter-buffer-substring beg end)))
>   (if transient-mark-mode
>       (setq deactivate-mark t))
>   nil)
>
> What is the "nil" doing at the end here? The syntax seems to be:
>
> (defun copy-region-as-kill (beg end) [...] nil)

I think the nil makes sure the function returns nil and not anything
killed in the function body or so. Its seems to be a function called
only for its side-effects, not for its return value.

-- 
cheers,
Thorsten