From: Barry Margolin <barmar@alum.mit.edu>
To: help-gnu-emacs@gnu.org
Subject: Re: never use `eval' (was: Re: How to mapcar or across a list?)
Date: Wed, 15 Jul 2015 20:04:23 -0400 [thread overview]
Message-ID: <barmar-1DA32E.20042315072015@88-209-239-213.giganet.hu> (raw)
In-Reply-To: mailman.6984.1437004760.904.help-gnu-emacs@gnu.org
In article <mailman.6984.1437004760.904.help-gnu-emacs@gnu.org>,
Emanuel Berg <embe8573@student.uu.se> wrote:
> John Mastro <john.b.mastro@gmail.com> writes:
>
> > I would use something like this:
> >
> > (defmacro ...
>
> Macros never liked me, and that is mutual. Are they
> really preferrable to `eval'?
>
> > For this (and others like it)
>
> ... which are? Do you mean the eval + backquote combo?
>
> > it looks like you could instead simply use e.g.
> > (apply #'create-book nil title data)
>
> This is what it looks like:
>
> (eval `(create-book nil ,title ,@data))
>
> With `apply', won't the last "data" be a list, i.e.
>
> (a b ... n)
>
> instead of
>
> a b ... n
>
> ?
No. apply spreads its last argument. You're thinking of funcall.
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
next prev parent reply other threads:[~2015-07-16 0:04 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 20:14 How to mapcar or across a list? Marcin Borkowski
2015-07-15 20:42 ` Rasmus
2015-07-15 20:55 ` Marcin Borkowski
2015-07-15 22:21 ` Emanuel Berg
2015-07-15 22:21 ` John Mastro
[not found] ` <mailman.6977.1436998965.904.help-gnu-emacs@gnu.org>
2015-07-15 22:28 ` Pascal J. Bourguignon
2015-07-15 22:36 ` Emanuel Berg
2015-07-15 22:57 ` never use `eval' (was: Re: How to mapcar or across a list?) Emanuel Berg
2015-07-15 23:27 ` John Mastro
2015-07-15 23:57 ` Emanuel Berg
2015-07-16 0:18 ` John Mastro
[not found] ` <mailman.6984.1437004760.904.help-gnu-emacs@gnu.org>
2015-07-16 0:04 ` Barry Margolin [this message]
[not found] ` <mailman.6982.1437001117.904.help-gnu-emacs@gnu.org>
2015-07-16 0:01 ` Barry Margolin
2015-07-16 1:13 ` Emanuel Berg
2015-07-17 0:55 ` Emanuel Berg
[not found] ` <mailman.7027.1437094623.904.help-gnu-emacs@gnu.org>
2015-07-17 1:39 ` never use `eval' Pascal J. Bourguignon
2015-07-17 2:16 ` Emanuel Berg
2015-07-17 8:36 ` Barry Margolin
2015-07-17 8:55 ` Pascal J. Bourguignon
2015-07-16 0:22 ` Pascal J. Bourguignon
2015-07-16 1:11 ` Emanuel Berg
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