Re: How to delete all nil properties from a plist?

["Pascal J. Bourguignon" <pjb@informatimago.com>]

Marcin Borkowski <mbork@mbork.pl> writes:

> OK, so what about this?  Is there a better way (which would probably
> mean, is such function already defined)?
>
> (defun alist-clear (alist)
>   "Return ALIST with all pairs with nil value deleted."
>   (if alist

Better use when in this case.

>     (if (cdar alist)
> 	      (cons (car alist)
>     	        (alist-clear (cdr alist)))

The bad thing (shared with your plist-clear) of this, is that it's a
non-terminal recursive call, and therefore it will use O(n) stack space
with n = (length alist).  Ie. it will break for not so long alists.

See the variable max-lisp-eval-depth.

> 	      (alist-clear (cdr alist)))))


-- 
__Pascal Bourguignon__                 http://www.informatimago.com/
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