From: Navy Cheng <navych@126.com>
To: help-gnu-emacs@gnu.org
Subject: Re: How to use a symbol and its value to create alist?
Date: Wed, 12 Aug 2015 09:57:13 +0800 [thread overview]
Message-ID: <20150812015712.GC22098@debian> (raw)
In-Reply-To: <87pp2tga8e.fsf@kuiper.lan.informatimago.com>
On Tue, Aug 11, 2015 at 04:39:45PM +0200, Pascal J. Bourguignon wrote:
> Navy Cheng <navych@126.com> writes:
>
> > For example:
> >
> > (setq a 1)
> > (setq b 2)
> > (setq c 3)
> >
> > How can I a alist, like:
>
> How can you WHAT a alist?
Sorry for that, (setq WHAT "create")
>
> > ((a . 1) (b . 2) (c .3))
> >
> > The value of a, b and c may change, so don't do this like
> > (setq tree ((a . 1) (b . 2) (c .3)))
>
> This is not a valid form, because (a . 1) is not a function name,
> therefore it's not possible to apply it.
>
Sorry again, (setq tree '((a . 1) (b . 2) (c .3)))
>
> If you want to BUILD an a-list, you can use acons:
>
> (let ((a 1)
> (b 2)
> (c 3))
> (let ((tree (acons 'a a (acons 'b b (acons 'c c '())))))
> tree))
> --> ((a . 1) (b . 2) (c . 3))
>
Thanks for your patient and help. Your answer is OK. I have learned
another way to do this.
(setq tree `((a . ,a) (b . ,b) (c . ,c)))
next prev parent reply other threads:[~2015-08-12 1:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.8135.1439301205.904.help-gnu-emacs@gnu.org>
2015-08-11 14:39 ` How to use a symbol and its value to create alist? Pascal J. Bourguignon
2015-08-12 1:57 ` Navy Cheng [this message]
2015-08-12 0:21 ` Barry Margolin
2015-08-12 1:35 ` Navy Cheng
2015-08-11 13:52 Navy Cheng
2015-08-11 15:21 ` Ian Zimmerman
2015-08-12 1:46 ` Navy Cheng
[not found] ` <mailman.8160.1439343998.904.help-gnu-emacs@gnu.org>
2015-08-12 2:12 ` Pascal J. Bourguignon
2015-08-12 2:18 ` Pascal J. Bourguignon
2015-08-12 5:06 ` Navy Cheng
[not found] ` <mailman.8170.1439355992.904.help-gnu-emacs@gnu.org>
2015-08-12 7:03 ` Pascal J. Bourguignon
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