From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Kevin Rodgers Newsgroups: gmane.emacs.bugs Subject: bug#5971: 23.1.95; `delete' modifies default value instead of buffer-local value Date: Wed, 21 Apr 2010 01:29:33 -0600 Message-ID: References: <1ED47ADCD80A4C019EF77D4CB7C5D863@us.oracle.com><8348D62071EB468F8FD5D95D35201C08@us.oracle.com><8092CBDD05AF419298FFE73B27D1E5C7@us.oracle.com><6CC9DF69BADF4A27825D1A0BDE4219F1@us.oracle.com><1D1CB64F606C49129227A1B34D69EB26@us.oracle.com> <3DF341479674474FA6D1DD5F0DE03543@us.oracle.com> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1271845128 15275 80.91.229.12 (21 Apr 2010 10:18:48 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 21 Apr 2010 10:18:48 +0000 (UTC) To: bug-gnu-emacs@gnu.org Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Wed Apr 21 12:18:46 2010 connect(): No such file or directory Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1O4X0w-0000Gy-Jo for geb-bug-gnu-emacs@m.gmane.org; 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Wed, 21 Apr 2010 09:29:44 +0200 Original-Received: from kevin.d.rodgers by c-71-237-24-138.hsd1.co.comcast.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 21 Apr 2010 09:29:44 +0200 X-Injected-Via-Gmane: http://gmane.org/ connect(): No such file or directory Original-Lines: 28 Original-X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: c-71-237-24-138.hsd1.co.comcast.net User-Agent: Thunderbird 2.0.0.24 (Macintosh/20100228) In-Reply-To: <3DF341479674474FA6D1DD5F0DE03543@us.oracle.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.11 Precedence: list Resent-Date: Wed, 21 Apr 2010 05:59:01 -0400 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:36395 Archived-At: Drew Adams wrote: >>> If there is _no_ buffer-local value, then the default value >>> is returned for the var. >> Exactly. > > OK, I get it. > > The problem was that the defvar defined a default value that was a particular > cons cell. Then, I set the buffer-local value to (a modification of) that list > structure, since the initial value returned by the variable was the default one. > IOW, in the setq, it was the right-hand side, where the variable's value was > used, that was the problem. > > Before closing the bug, please consider adding something to the doc that might > make this gotcha clearer. Perhaps something like this: > > Although `make-variable-buffer-local' makes its argument variable become buffer > local whenever it is set, any references to the variable before it is set return > its default value. That includes any occurrences of the variable in an > expression used to calculate the new, buffer-local value. That is implied by the fact that make-variable-buffer-local is a function (vs. macro vs. special form): its argument forms are evaluated before being passed to the function by eval. -- Kevin Rodgers Denver, Colorado, USA