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From: David Kastrup <dak@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: Creating a list
Date: Thu, 19 Nov 2009 09:35:25 +0100	[thread overview]
Message-ID: <87y6m2kj3m.fsf@lola.goethe.zz> (raw)
In-Reply-To: 87k4xnge1t.fsf@Traian.DecebalComp

Cecil Westerhof <Cecil@decebal.nl> writes:

> At the moment I create a list with:
>       (setq ret-val (cons total-amount (cons current-amount ())))
> I thought about doing it with:
>       (setq ret-val (cons total-amount '(current-amount)))
>
> But then the second value is the string current-amount

Wrong.  The _symbol_ current-amount.

> instead of the value of current-amount. Is there a better way to build
> the list? At this moment it is not a problem, but when I want to build
> a list from 30 values ...

I would really recommend taking a look at the Introduction to Elisp
Programming

(info "(eintr)")
Press C-x C-e here --^

This is sort of obvious:

(setq ret-val (list total-amount current-amount))

If you have a large piece of structure around the variable values and
would prefer to write it in its unevaluated form, you can also use

(setq ret-val `(,total-amount ,current-amount))

namely backquote the entire structure, and put a comma before everything
within the structure that is to evaluated instead of quoted.  After
byte-compilation, the resulting code is rather the same.

-- 
David Kastrup


  reply	other threads:[~2009-11-19  8:35 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-19  7:38 Creating a list Cecil Westerhof
2009-11-19  8:35 ` David Kastrup [this message]
2009-11-19 10:59   ` Cecil Westerhof
2009-11-19 11:41     ` David Kastrup
2009-11-19 13:13       ` Cecil Westerhof
2009-11-19 13:47         ` Barry Margolin
2009-11-19 15:11           ` Cecil Westerhof
2009-11-19 19:26             ` Pascal J. Bourguignon
2009-11-19 13:57         ` David Kastrup
2009-11-19 15:14           ` Cecil Westerhof
2009-11-19 13:59         ` Pascal J. Bourguignon
2009-11-19 11:59   ` Gnus: Some new mails are automatically marked as 'O' Wang Lei

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