From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Jean Louis Newsgroups: gmane.emacs.help Subject: Re: How to avoid compiler warning `unused lexical variable' for `dolist' or `dotimes'? Date: Fri, 8 Jan 2021 05:38:14 +0300 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="27792"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mutt/2.0 (3d08634) (2020-11-07) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 08 03:38:49 2021 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 1kxhft-00079I-B9 for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 08 Jan 2021 03:38:49 +0100 Original-Received: from localhost ([::1]:50200 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kxhfs-0001fK-D6 for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 07 Jan 2021 21:38:48 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:60090) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxhfZ-0001fD-Tu for help-gnu-emacs@gnu.org; Thu, 07 Jan 2021 21:38:29 -0500 Original-Received: from stw1.rcdrun.com ([217.170.207.13]:58507) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxhfX-0000mt-Th for help-gnu-emacs@gnu.org; Thu, 07 Jan 2021 21:38:29 -0500 Original-Received: from localhost ([::ffff:41.210.145.49]) (AUTH: PLAIN securesender, TLS: TLS1.2,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by stw1.rcdrun.com with ESMTPSA id 0000000000295443.000000005FF7C5A1.0000483D; Thu, 07 Jan 2021 19:38:24 -0700 Mail-Followup-To: help-gnu-emacs@gnu.org Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=217.170.207.13; envelope-from=bugs@gnu.support; helo=stw1.rcdrun.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.io gmane.emacs.help:127077 Archived-At: * Stefan Monnier [2021-01-08 05:22]: > >> Indeed, I don't like this 3-arg form of `dotimes` and `dolist` because > >> it tends to "hide" the return value. But we keep it because there's > >> something to be said for not being "gratuitously" different from > >> Common-Lisp. > > > > I do not see how it hides when I know how it is used from Common > > Lisp. So I look there in third value and I know which one will be > > returned. > > It's hidden because it's not at the usual place where the return value > is usually placed (i.e. in the last expression). I understand your viewpoint. But I learned it in Common Lisp and for me it is not hidden. I know that nothing will be returned unless declared what to return. And I just guess, that `dotimes' was included in Emacs Lisp as to duplicate Common Lisp. However, I try to have Emacs Lisp mostly clean from Common Lisp constructs. So I may change my `dotimes' forms into `while' forms or where it applies to some of the mapping functions. > In contrast in `dotimes` and `dolist` it's placed in > a sub-sub-expression and moreover it's one that's rarely used (arguably > *because* it's too deeply nested), so you're likely to miss it if you > don't go looking for it very actively. > > Not that it matters anyway Maybe somebody would miss, but I don't. This may be because forms I have are rather short, example: (defun pct-plus (amount percent) "Return AMOUNT increased for PERCENT of it." (let* ((percent (* amount percent)) (result (+ amount percent))) result)) (defun pct-plus-times (amount percent times) "Return AMOUNT increased for PERCENT for number of TIMES." (dotimes (var times amount) (setq amount (pct-plus amount percent)))) And I see that `var' is unused there. I have never used those functions in a package so there were no warnings. Then I can replace the above function to following: (defun pct-plus-times (amount percent times) "Return AMOUNT increased for PERCENT for number of TIMES." (let ((n 0)) (while (/= n times) (setq amount (pct-plus amount percent)) (setq n (1+ n))) amount)) And it does the same hopefully, it appears to me more Emacs Lisp-ish, but looks uglier, though it is more understandable to me and it is the kind of what I learned about loops from old times.