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 19:01:14 +0300 Message-ID: References: <87skbg8jww.fsf@galatea.local> <87bpi1n1z7.fsf@galatea.local> <873a3dmvef.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 1260806586 15427 80.91.229.12 (14 Dec 2009 16:03:06 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 14 Dec 2009 16:03:06 +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 17:02:56 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 1NKDNr-0000de-Mg for geh-help-gnu-emacs@m.gmane.org; Mon, 14 Dec 2009 17:02:52 +0100 Original-Received: from localhost ([127.0.0.1]:37793 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NKDNr-0002xL-Nd for geh-help-gnu-emacs@m.gmane.org; Mon, 14 Dec 2009 11:02:51 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NKDMo-0002kT-Hz for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 11:01:46 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NKDMj-0002jg-GA for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 11:01:45 -0500 Original-Received: from [199.232.76.173] (port=40182 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NKDMj-0002jd-87 for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 11:01:41 -0500 Original-Received: from lo.gmane.org ([80.91.229.12]:54775) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NKDMi-0007JT-Hm for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 11:01:40 -0500 Original-Received: from list by lo.gmane.org with local (Exim 4.50) id 1NKDMf-0008UL-OG for help-gnu-emacs@gnu.org; Mon, 14 Dec 2009 17:01:37 +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 17:01:37 +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 17:01:37 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 119 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:70642 Archived-At: pjb@informatimago.com (Pascal J. Bourguignon) writes: > Sergei Organov writes: > >> 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. > > Of course. You do that only while "debugging" ewoc-collect. Then you > can either put back the old nreverse, or reboot emacs. > > (require 'cl) > (setf (symbol-function 'old-nreverse) (symbol-function 'nreverse)) > (defun nreverse (&rest arguments) > (message "nreverse called with %S" arguments) > (funcall old-nreverse arguments)) > ;; possibly add an advice, but you can as well put the code in the > ;; new definition of nreverse above. > (do-stuff-with-new-nreverse) > > ;; When done: > (setf (symbol-function 'nreverse) (symbol-function 'old-nreverse)) I'm not now sure, but I think I've tried replacing defadvice with re-defining of the function, but it worked (didn't work) exactly the same way as defadvice. >> 2. I don't know how to reload `ewoc-collect' (from elisp) provided it's >> already byte-compiled. > > C-h f ewoc-collect RET C-x o TAB RET > > should bring you to the file where ewoc-collect is defined. Then you > can load it, or just re-evaluate the ewoc-collect definition to have > it take into account the new nreverse. If you want to debug it while > compiled, you can byte-compile it too. > You see, I wanted automatic elisp-only solution to "fixing" ewoc-collect, but only if it indeed happens to be buggy. Manual reloading is not an option then. Alternate approach would be to execute simple test-case to determine if ewoc-collect is indeed buggy and then re-define it to the correct version if so. That's what I'm going to implement now, provided there doesn't seem to be a way to do what I want by means of advising ewoc-collect and nreverse. > >> 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 > > Then you know where ewoc-collect is defined, you can load this ewoc.el > file! I do know, but I wanted lisp-only, entirely automated solution. -- Sergei.