From: Rolf Ade <rolf@pointsman.de>
To: emacs-tangents@gnu.org
Subject: Re: 2016-05-23 Emacs News
Date: Fri, 10 Jun 2016 02:04:05 +0200 [thread overview]
Message-ID: <87bn39ewp6.fsf@linux-qg7d.fritz.box> (raw)
In-Reply-To: 87lh30iv18.fsf@sachachua.com
Sacha Chua <sacha@sachachua.com> writes:
> 2016-05-23 Emacs News
>
> * Coding:
>
> * Literal values and destructive functions
(That is:
http://mbork.pl/2016-05-23_Literal_values_and_destructive_functions)
Wait, what?
Sure, sort is documented as modifying the LIST in place. And the setq
makes `foo` global, so ... maybe no surprise, or so. But if I eval
(defun destructive-havoc ()
"Example of destructive havoc."
(let ((foo '(1 3 2)))
(message "before sort, foo is: %s" foo)
(sort foo #'<)
(message "after sort, foo is: %s" foo)))
and M-: (destructive-havoc) two times, I still get
before sort, foo is: (1 3 2)
after sort, foo is: (1 2 3)
before sort, foo is: (1 2 3)
after sort, foo is: (1 2 3)
in *Messages*. Could someone please explain that to me?
next prev parent reply other threads:[~2016-06-10 0:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-23 16:44 2016-05-23 Emacs News Sacha Chua
2016-06-10 0:04 ` Rolf Ade [this message]
2016-06-10 10:30 ` Nicolas Richard
2016-06-10 13:37 ` Rolf Ade
2016-06-10 13:52 ` Marcin Borkowski
2016-06-10 15:22 ` Rolf Ade
2016-06-10 16:45 ` John Mastro
2016-06-10 14:55 ` Nicolas Richard
2016-06-10 16:01 ` Rolf Ade
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