From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Sergei Organov Newsgroups: gmane.emacs.help Subject: Re: Problem advising nreverse. Date: Mon, 14 Dec 2009 18:05:23 +0300 Message-ID: References: <87skbg8jww.fsf@galatea.local> <87bpi1n1z7.fsf@galatea.local> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1260804262 6427 80.91.229.12 (14 Dec 2009 15:24:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 14 Dec 2009 15:24:22 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Mon Dec 14 16:24:16 2009 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1NKCmV-0007Xh-DP for geh-help-gnu-emacs@m.gmane.org; Mon, 14 Dec 2009 16:24:15 +0100 Original-Received: from localhost ([127.0.0.1]:42561 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NKCmV-0000KJ-4o for geh-help-gnu-emacs@m.gmane.org; Mon, 14 Dec 2009 10:24:15 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NKCXL-0000at-0L for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 10:08:35 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NKCXG-0000Te-7o for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 10:08:34 -0500 Original-Received: from [199.232.76.173] (port=58195 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NKCXG-0000TT-3d for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 10:08:30 -0500 Original-Received: from lo.gmane.org ([80.91.229.12]:44644) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NKCXF-00005a-HS for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 10:08:29 -0500 Original-Received: from list by lo.gmane.org with local (Exim 4.50) id 1NKCVt-0008MH-98 for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 16:07:05 +0100 Original-Received: from 89.175.180.246 ([89.175.180.246]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 14 Dec 2009 16:07:05 +0100 Original-Received: from osv by 89.175.180.246 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 14 Dec 2009 16:07:05 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 78 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 89.175.180.246 User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:70640 Archived-At: pjb@informatimago.com (Pascal J. Bourguignon) writes: > Sergei Organov writes: > >> pjb@informatimago.com (Pascal J. Bourguignon) writes: >>> Sergei Organov writes: >>> >>>> Hello, >>>> >>>> It seems that an advice set for `nreverse' function fails to be called >>>> when `nreverse' is called from a byte compiled function: >> >> [...] >> >>>> Is it bug or feature? What's going on here? >>> >>> Indeed, it is a feature. >>> >>> Advices are not available from several call points: >>> >>> 1- when the advised function is called from C code. >>> >>> 2- when the advised function is a an opcode of the virtual machine. >>> You can observe the difference between the two primitives nreverse >>> and buffer-name for example, with: >>> >>> (disassemble (byte-compile (lambda (x) (nreverse x)))) >>> vs.: >>> (disassemble (byte-compile (lambda (x) (buffer-name x)))) >>> >>> In the former case, nreverse is a byte code, and therefore no >>> advice applies. In the later case, buffer-name is called with the >>> call byte code, which will go thru the advice. >>> >>> Notice that if you really want to advice such a low level primitive >>> function as nreverse, you can replace it with a lisp function (and >>> recompile all the code that uses it). >> >> Thanks a lot for the explanations and suggestion. >> >> Unfortunately this is not an option as intention was to advise >> `nreverse' during calls to a possibly buggy `ewoc-collect' function that >> for a long time errorneously called `nreverse' at the end (fixed since >> 2008). > > Redefining nreverse and reloading the ewoc-collect function would help > as indicated... Yeah, but: 1. I don't really want `nreverse' to be always redefined. 2. I don't know how to reload `ewoc-collect' (from elisp) provided it's already byte-compiled. Here what I've actually originally tried (that didn't work): (defadvice ewoc-collect (around fix-ewoc-collect activate) "Fix buggy `ewoc-collect' by reversing its result provided it was altered by `nreverse'." (let ((last-nreverse-result)) (unwind-protect (progn (defadvice nreverse (after notice-nreverse activate) (setq last-nreverse-result ad-return-value)) ad-do-it) (ad-unadvise 'nreverse)) (if (eq last-nreverse-result ad-return-value) (setq ad-return-value (nreverse ad-return-value))))) This starts to work as soon as I re-evaluate the (defun ewoc-collect ...) in the ewoc.el file after the above defadvice is evaluated and continues to work even if I byte-compile the (defun ewoc-collect...) after that (though I still don't understand why it works after byte-compiling), but then it's both easier and cleaner to just re-define ewoc-collect to a correct version. -- Sergei.