From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg Newsgroups: gmane.emacs.help Subject: Re: Passing optional arguments for use with internal functions Date: Thu, 03 Aug 2023 17:25:23 +0200 Message-ID: <87bkfokv18.fsf@dataswamp.org> References: <0Ezo2Srah2_DE-D1XG3MBYVEmAvnfHLu8cKpS3oJa4Hn5ADeV7sBbHFTtIzRAFv461O5XlpcjkyImCJHO7DKvaM492vQW7cz9wXL_VaDAdQ=@proton.me> <87tttoux4p.fsf@dataswamp.org> <87o7jwufju.fsf@dataswamp.org> <87y1iwe06a.fsf@dataswamp.org> <87leetl30m.fsf@dataswamp.org> <-3N3ToZTUg2mUqmpgTYmAX8LUtMKCkCb5CLWN1q1gJxpBpcd_18KWXjL7lh51B6NXfrXEBNmRo7SwK5AClT6M1-NjD2DP1oInylqklgCF9Y=@proton.me> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="19677"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:JiUEhaJg4CjynRL7HXUqZxJY6Dw= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Aug 04 20:25:41 2023 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 1qRzUb-0004wR-0F for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 04 Aug 2023 20:25:41 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qRzUK-00045Q-Pp; Fri, 04 Aug 2023 14:25:25 -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 1qRaCm-00013B-3o for help-gnu-emacs@gnu.org; Thu, 03 Aug 2023 11:25:36 -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 1qRaCj-00015J-5F for help-gnu-emacs@gnu.org; Thu, 03 Aug 2023 11:25:34 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1qRaCf-0008gQ-Tv for help-gnu-emacs@gnu.org; Thu, 03 Aug 2023 17:25:29 +0200 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never 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: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Fri, 04 Aug 2023 14:25:20 -0400 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:144591 Archived-At: uzibalqa wrote: > What I did not immediately realise was that within the > context of function arguments, lexical binding is the > default way to handle function arguments in Lisp and Emacs > Lisp, notwithstanding the file binding specification. Here, take a look at this code. First the scope is set to lexical which you should always do, but here it doesn't influence the code. Then a global/special/dynamic variable is created with `defvar'. Then a lexical argument with the same name is created, and that will be the boss for every mention in that function. If you byte-compile it, you will get a warning, but that is just to avoid confusion, the code will be more clear if the argument is named something else. Warning: global/dynamic var ‘gsd’ lacks a prefix Warning: Lexical argument shadows the dynamic variable gsd ;;; -*- lexical-binding: t -*- (defvar gsd 1) (defun test-gsd (&optional gsd) (or gsd (setq gsd 2)) gsd) ;; (test-gsd) ;; (test-gsd 3) -- underground experts united https://dataswamp.org/~incal