From: "Drew Adams" <drew.adams@oracle.com>
To: "'Barry Margolin'" <barmar@alum.mit.edu>, <help-gnu-emacs@gnu.org>
Subject: RE: alists with precomputed variables
Date: Tue, 20 Jan 2009 23:54:14 -0800 [thread overview]
Message-ID: <004b01c97b9d$752487a0$0200a8c0@us.oracle.com> (raw)
In-Reply-To: <barmar-B5083B.00492321012009@mara100-84.onlink.net>
> > (setq my-alist `((p1 . 10) (p2 ,@my-var)))
>
> I guess that might work, but ,@ is supposed to be followed by an
> expression that returns a list, so that it can be spliced into the
> containing list. It would be better to write:
>
> (setq my-alist `((p1 . 10) (p2 . ,my-var)))
I don't know about "supposed to be" (not only lists are spliced into list
structure), but yes, `.' followed by `,' might be clearer for an atom. But if I
didn't know the value of `my-var', I would probably use `,@', personally.
Anyway, the important thing is to read up on lists in the doc.
There are several ways to get something like what was requested.
The variants I gave are not all equivalent, in any case. In particular, '(p1 .
10) is typically not the same as (cons 'p1 10), in many contexts.
prev parent reply other threads:[~2009-01-21 7:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-21 5:03 alists with precomputed variables Erik Iverson
2009-01-21 5:13 ` Drew Adams
[not found] ` <mailman.5420.1232514814.26697.help-gnu-emacs@gnu.org>
2009-01-21 5:49 ` Barry Margolin
2009-01-21 7:54 ` Drew Adams [this message]
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