From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: How to tame compiler? Date: Fri, 30 Apr 2021 18:20:26 -0400 Message-ID: References: <874kfn292f.fsf@disroot.org> <87eeerh1g9.fsf@zoho.eu> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="34509"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:qpPq8IyG1LbF4dAixCVplU497Nc= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat May 01 00:21:14 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 1lcbVa-0008sh-HK for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 01 May 2021 00:21:14 +0200 Original-Received: from localhost ([::1]:52312 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lcbVZ-0001aQ-9l for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 30 Apr 2021 18:21:13 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:50166) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lcbUx-0001a3-Q5 for help-gnu-emacs@gnu.org; Fri, 30 Apr 2021 18:20:35 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]:42906) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lcbUv-0003pk-IA for help-gnu-emacs@gnu.org; Fri, 30 Apr 2021 18:20:34 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1lcbUt-00086d-1C for help-gnu-emacs@gnu.org; Sat, 01 May 2021 00:20:31 +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: 2.1.23 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:129233 Archived-At: Emanuel Berg via Users list for the GNU Emacs text editor [2021-05-01 00:06:30] wrote: > Jorge P. de Morais Neto wrote: >>>> Is there a way to avoid these warnings? >>> Yes: don't abuse `eval` ;-) > Stefan Monnier who wrote that last part, or anyone else for > that matter, what is the rule of thumb when to and when not to > use `eval'? Use it only when you have to, otherwise don't use it. > (let ((cmd (cl-find-if (lambda (c) > (and (eq (car c) #'wrap-search) > (not (string= (cl-caddr c) "")) )) > command-history) )) > (if cmd > (if (= new-options 1) > (eval cmd) Here, as in your other example, you have to use `eval`, because `command-history` was defined to contain a list of ELisp expressions and those can't be used other than via `eval`. So I'll grant you a pass for this time. If you were in a position to control the format of history variable, then you wouldn't have to use `eval` here, OTOH: you could define that variable to hold a list of *functions* and you'd just use `funcall` instead of `eval`. Stefan