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: get nargs for a function Date: Sat, 29 Aug 2015 17:41:24 -0400 Message-ID: References: <9eb51198-614a-49f7-8085-2a068dd28852@googlegroups.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1440884528 1370 80.91.229.3 (29 Aug 2015 21:42:08 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 29 Aug 2015 21:42:08 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sat Aug 29 23:42:00 2015 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 1ZVnss-0005nc-C0 for geh-help-gnu-emacs@m.gmane.org; Sat, 29 Aug 2015 23:41:58 +0200 Original-Received: from localhost ([::1]:54818 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZVnsr-0003pX-U9 for geh-help-gnu-emacs@m.gmane.org; Sat, 29 Aug 2015 17:41:57 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:53435) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZVnsg-0003pA-Jn for help-gnu-emacs@gnu.org; Sat, 29 Aug 2015 17:41:47 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZVnsc-00029H-4b for help-gnu-emacs@gnu.org; Sat, 29 Aug 2015 17:41:45 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:46183) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZVnsb-00028p-Tj for help-gnu-emacs@gnu.org; Sat, 29 Aug 2015 17:41:42 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ZVnsY-0005SW-S1 for help-gnu-emacs@gnu.org; Sat, 29 Aug 2015 23:41:39 +0200 Original-Received: from 104-222-112-193.cpe.teksavvy.com ([104.222.112.193]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 29 Aug 2015 23:41:38 +0200 Original-Received: from monnier by 104-222-112-193.cpe.teksavvy.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 29 Aug 2015 23:41:38 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 16 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 104-222-112-193.cpe.teksavvy.com User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) Cancel-Lock: sha1:X7tdyrHNq9pFKh3KmNBPsMjC/iA= 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:106921 Archived-At: > Is there a built in way to return the arg list (actually just the number of > args) for a function that has been passed to me? The answer is "yes, but fundamentally no". The reason it's fundamentally no, is that you'd need to answer questions such as "how many arguments does cl-member take". In most cases, the better approach is to do something else, such as: (condition-case (funcall thefunction arg1 arg2 ...) (wrong-number-of-arguments ...do-something-else...)) -- Stefan