byte-opt.el: byte-optimize-backward-word

byte-opt.el: byte-optimize-backward-word

[sri]

Using GNU Emacs 21.3.1 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
        of 2004-07-07 on localhost.localdomain.

In byte-opt.el:

(put 'backward-word 'byte-optimizer 'byte-optimize-backward-word)
(defun byte-optimize-backward-word (form)
  (cond ((and (= 2 (safe-length form))
	      (numberp (nth 1 form)))
	 (list 'forward-word (eval (- (nth 1 form)))))
	((= 1 (safe-length form))
	 '(forward-char -1))
;-------------^
        (t form)))

Shouldn't that be (forward-word -1)?  Also, backward-word requires an
argument; so, shouldn't Emacs complain here when it encounters 
backward-word without an argument.  (IIRC, several other optimizer
functions do something similar -- provide arguments when none is
there, for functions that require it.)

-Sriram

Re: byte-opt.el: byte-optimize-backward-word

[Andreas Schwab]

sri@asu.edu writes:

> In byte-opt.el:
>
> (put 'backward-word 'byte-optimizer 'byte-optimize-backward-word)
> (defun byte-optimize-backward-word (form)
>   (cond ((and (= 2 (safe-length form))
> 	      (numberp (nth 1 form)))
> 	 (list 'forward-word (eval (- (nth 1 form)))))
> 	((= 1 (safe-length form))
> 	 '(forward-char -1))
> ;-------------^
>         (t form)))
>
> Shouldn't that be (forward-word -1)?

Yes, you are right.  Looks like a pasto.  And a rather old one.

> Also, backward-word requires an argument;

Not any more.  The argument is now optional in CVS.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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"And now for something completely different."

Re: byte-opt.el: byte-optimize-backward-word

[Richard Stallman]

Thanks for finding this bug.  In the latest Emacs,
the argument to backward-word is optional, so it is a
real bug.  I will fix it.