From: Kevin Rodgers <ihs_4664@yahoo.com>
Subject: Re: replacing a certain element in a list with another
Date: Thu, 23 Oct 2003 09:30:42 -0600 [thread overview]
Message-ID: <3F97F422.2030307@yahoo.com> (raw)
In-Reply-To: jwvoew8xcc2.fsf-monnier+gnu.emacs.help@vor.iro.umontreal.ca
Stefan Monnier wrote:
>Roland Winkler wrote:
>>It might be helpful to add a comment to the docstring or info page
>>for nreverse saying that its argument is modified such that
>>afterwards it is a 1-element list containing the last element of the
>>reversed list.
>
> I don't think this particular aspect of the behavior should be documented.
> Maybe we should add a note saying "the argument should not be used
> afterwards", but even that would not be very convincing.
> I think the only reasonable thing to put is a "don't use this unless you
> know what you're doing".
Why not document all the destructive list operations like delq, whose
doc string says:
If the first member of LIST is ELT, there is no way to remove it by side
effect; therefore, write `(setq foo (delq element foo))' to be sure of
changing the value of `foo'.
For nreverse, it would be:
Because the first cons cell of LIST is the last cons cell of the
returned list, write `(setq foo (nreverse foo))' to set `foo' to its
reversed value.
--
Kevin Rodgers
parent reply other threads:[~2003-10-23 15:30 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <jwvoew8xcc2.fsf-monnier+gnu.emacs.help@vor.iro.umontreal.ca>]
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