From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: replacing a function with another one Date: Wed, 12 Mar 2014 14:26:43 -0400 Message-ID: References: <87vbvofsi6.fsf@yun.yagibdah.de> <87bnxgs4r9.fsf@web.de> <87lhwj1cfz.fsf@yun.yagibdah.de> <87zjkz6vd5.fsf@web.de> <8738ir161u.fsf@yun.yagibdah.de> <87eh2b6nfm.fsf@web.de> <87r46anab5.fsf@yun.yagibdah.de> <87wqg2u77k.fsf@web.de> <87pplugjh6.fsf@yun.yagibdah.de> <8738ipd2kh.fsf@web.de> <87y50gj1uf.fsf@yun.yagibdah.de> <874n34ticd.fsf@web.de> <87zjkvms1j.fsf@yun.yagibdah.de> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1394648849 17345 80.91.229.3 (12 Mar 2014 18:27:29 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 12 Mar 2014 18:27:29 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Mar 12 19:27:37 2014 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WNnsP-0001M8-FV for geh-help-gnu-emacs@m.gmane.org; Wed, 12 Mar 2014 19:27:37 +0100 Original-Received: from localhost ([::1]:34096 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNnsP-0001Ha-1p for geh-help-gnu-emacs@m.gmane.org; Wed, 12 Mar 2014 14:27:37 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54455) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNns1-00010j-6d for help-gnu-emacs@gnu.org; Wed, 12 Mar 2014 14:27:20 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WNnrs-0005JK-W5 for help-gnu-emacs@gnu.org; Wed, 12 Mar 2014 14:27:13 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:48776) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNnrs-0005JE-Pj for help-gnu-emacs@gnu.org; Wed, 12 Mar 2014 14:27:04 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1WNnro-0000iW-W7 for help-gnu-emacs@gnu.org; Wed, 12 Mar 2014 19:27:00 +0100 Original-Received: from 76-10-154-114.dsl.teksavvy.com ([76.10.154.114]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 12 Mar 2014 19:27:00 +0100 Original-Received: from monnier by 76-10-154-114.dsl.teksavvy.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 12 Mar 2014 19:27:00 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 42 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 76-10-154-114.dsl.teksavvy.com User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) Cancel-Lock: sha1:Pxt5/HK2zUoUiVCLq/HFYT/hGo4= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:96473 Archived-At: > That line doesnīt tell me anything, it only confuses me. Probably because you don't understand (lambda ...) yet. > (defun replacement-fn (original-fn-arg0 original-fn-arg1) > (foobar) > (original-fn original-fn-arg0 original-fn-arg1) > (barfoo)) > (callinstead original-fn replacement-fn) That's pretty much exactly what advice-add does for :around, except that the original-fn is provided as an additional argument, so you have to write: (defun replacement-fn (orig-fun original-fn-arg0 original-fn-arg1) (foobar) (funcall orig-fun original-fn-arg0 original-fn-arg1) (barfoo)) (advice-add 'original-fn :around 'replacement-fn) > That would be clear and simple, assuming that calling the original > function from within a function that is defined to be called instead of > it always automatically calls the original function. That's one of the reasons why the original function is passed as an extra argument. This way you can choose to either call (original-fn ...) which will go through the advice recursively, or to call (funcall orig-fun ...) which will call the unadvised version. Magically making `original-fn' detect when it's called from its own advice and skip the advice in this case would be not only less general, but also pretty ugly to implement and unreliable. > You could also have `callbefore', `callafter', etc. Maybe itīs even > possible to implement this, using add-advice. Yup, just use :after or :before (in which case your advice won't receive the `orig-fun' argument). Stefan