From: Andrea Crotti <andrea.crotti.0@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: Add-to-list or setq append...
Date: Wed, 04 Aug 2010 10:02:42 +0200 [thread overview]
Message-ID: <m1y6cmhkkd.fsf@gmail.com> (raw)
In-Reply-To: 1CEA23A32F7043F282E60BDDC2485EB0@us.oracle.com
"Drew Adams" <drew.adams@oracle.com> writes:
>
> No, it is not. The former unconditionally adds the entry at the beginning of
> the alist. The latter adds the entry to the alist only if an `equal' entry is
> not already present.
>
> The former ensures that the entry is at the start of the list. The latter does
> not.
>
> In the former case the alist can end up with multiple entries with the given
> key, the first such entry shadowing all others with the same key. If you then
> pop off that first entry, the previously first of all entries with that key is
> still present and now becomes the one that matters (shadows any others with that
> key).
Sure but
--8<---------------cut here---------------start------------->8---
ELISP> my-l
((1 . 3)
(1 . 2))
ELISP> (add-to-list 'my-l '(2 . 3))
((2 . 3)
(1 . 3)
(1 . 2))
--8<---------------cut here---------------end--------------->8---
it actually not add it ONLY if they're really equal, which is desirable
in my opinion.
What's the point in having twice the same cons in auto-mode-alist?
Then the real difference is that I add in the end instead of at the
beginning, and in that case I don't shadow an already present value...
next prev parent reply other threads:[~2010-08-04 8:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 22:37 Add-to-list or setq append Andrea Crotti
2010-08-03 22:41 ` Richard Riley
2010-08-04 0:06 ` Andrea Crotti
2010-08-04 0:35 ` Drew Adams
2010-08-04 8:02 ` Andrea Crotti [this message]
2010-08-04 12:57 ` Andrea Crotti
2010-08-04 15:41 ` Drew Adams
[not found] ` <mailman.2.1280926672.16887.help-gnu-emacs@gnu.org>
2010-08-04 13:33 ` Pascal J. Bourguignon
2010-08-04 15:42 ` Drew Adams
[not found] ` <mailman.5.1280875308.9029.help-gnu-emacs@gnu.org>
2010-08-04 18:24 ` David Kastrup
[not found] <mailman.3.1280875040.9029.help-gnu-emacs@gnu.org>
2010-08-04 1:02 ` Pascal J. Bourguignon
2010-08-04 8:12 ` Tim X
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