Re: Using CL in Gnus

[Jesper Harder <harder@ifa.au.dk>]

sigurd@12move.de (Karl Pflästerer) writes:

> `dolist' could be used here.  That's in cl-macs.el so could be used
> with eval-when-compile and for a reader is easier to see what
> happens (IMO).

In Emacs 21.3 `dolist' has been promoted to subr.el, so it's not even
necessary to eval-when-compile.

> If we start No Gnus we should look for a lot of places in the code
> where mapping over a list is written like that:
>
>         (let ((lst inputlist))
>           (while lst
>             (do-something-with-list lst)
>             .
>             (setq lst (cdr lst))))
>
> To cdr-down a list is not uncommon (above code would be nicer as
> recursive version) but `dolist' is IMO a much better alternative at
> such places.

Yes.  But in a lot of places the list isn't copied first.  In that
case -- and if speed matters -- `dolist' would degrade performance and
consing slightly.