From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier via Users list for the GNU Emacs text editor Newsgroups: gmane.emacs.help Subject: Re: Defaulting optional numeric and string arguments Date: Thu, 12 Sep 2024 15:17:33 -0400 Message-ID: References: Reply-To: Stefan Monnier Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="11192"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:jvvsTiBtLKVzyiuZ4LRAx4NW56E= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Thu Sep 12 21:20:32 2024 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1sopMl-0002oQ-TN for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 12 Sep 2024 21:20:31 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sopMP-0002gQ-Hm; Thu, 12 Sep 2024 15:20:09 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sopMN-0002er-6f for help-gnu-emacs@gnu.org; Thu, 12 Sep 2024 15:20:07 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sopML-0006pT-NK for help-gnu-emacs@gnu.org; Thu, 12 Sep 2024 15:20:06 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1sopMI-0002FZ-9s for help-gnu-emacs@gnu.org; Thu, 12 Sep 2024 21:20:02 +0200 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -15 X-Spam_score: -1.6 X-Spam_bar: - X-Spam_report: (-1.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:147973 Archived-At: > I have an optional numeric argument n passed to a function. > > Am having difficulty setting a default for it to cater for both the > interactive and non-interactive cases. > > Is the below how to do it ? > > (setq n (if (or (not n) (not numberp n)) 0 n)) Traditionally the default numeric value for an absent prefix arg is 1 rather than 0. So if you can arrange to use 1 as default, it'll integrate better into the overall Emacs experience. Also you can simply the above to (unless (numberp n) (setq n 0)) > I also have an optional string bfrn, to which I am using > (setq bfrn (if (or (not bfrn) (string= bfrn "")) "Context" bfrn)) I'd recommend to ignore the "" case (i.e. change your callers and/or the interactive spec so they don't accidentally send the empty string (e.g. use `read-string` rather than `read-from-minibuffer`)) and just use: (unless bfrn (setq bfrn "Context")) - Stefan