From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Arbitrary function: find the number(s) of expected arguments Date: Sat, 19 Mar 2016 16:08:23 +0200 Message-ID: <83a8lu8srs.fsf@gnu.org> References: <56E8906C.5050405@lanl.gov> <83egb68vfy.fsf@gnu.org> <87zituefp9.fsf@web.de> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1458396547 29743 80.91.229.3 (19 Mar 2016 14:09:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 19 Mar 2016 14:09:07 +0000 (UTC) Cc: emacs-devel@gnu.org To: Michael Heerdegen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Mar 19 15:09:00 2016 Return-path: Envelope-to: ged-emacs-devel@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 1ahHYp-0006ds-36 for ged-emacs-devel@m.gmane.org; Sat, 19 Mar 2016 15:08:59 +0100 Original-Received: from localhost ([::1]:49001 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ahHYo-0003Tp-IE for ged-emacs-devel@m.gmane.org; Sat, 19 Mar 2016 10:08:58 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:50781) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ahHYl-0003PG-73 for emacs-devel@gnu.org; Sat, 19 Mar 2016 10:08:55 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ahHYh-0004YT-5a for emacs-devel@gnu.org; Sat, 19 Mar 2016 10:08:55 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:55989) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ahHYh-0004YG-2c; Sat, 19 Mar 2016 10:08:51 -0400 Original-Received: from 84.94.185.246.cable.012.net.il ([84.94.185.246]:3763 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ahHYg-0005zI-Da; Sat, 19 Mar 2016 10:08:50 -0400 In-reply-to: <87zituefp9.fsf@web.de> (message from Michael Heerdegen on Sat, 19 Mar 2016 14:54:10 +0100) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:201864 Archived-At: > From: Michael Heerdegen > Date: Sat, 19 Mar 2016 14:54:10 +0100 > > Eli Zaretskii writes: > > > Patches to add func-arity to Emacs are welcome. > > Question: Is this a reasonable way to go? Will `func-arity' be a good > solution for the issues we discussed here? Do you have a better solution to suggest? If so, let's hear it. > For example, if > > (defun f (a b) (list a b)) > > (defalias 'g (apply-partially #'f 1)) > > what would (func-arity 'g) return? Ideally, it should return (1 . 1). > Would that be useful? Why wouldn't it be? > What would it return for adviced functions? An advice can change the > arity of a function. Most do not, but most advices have an &rest args > signature. Any function can be adviced. If the solution handles this complication, then it will return an accurate result. If not, it will be a known limitation. > My question is if it is a good idea to invite users to rely on something > like `func-arity'. You could ask the same about subr-arity, couldn't you? And yet we do have it.