From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.help Subject: Re: [External] : Re: Why is defun not executed during load-file? Date: Mon, 31 May 2021 22:09:04 +0200 Message-ID: <87pmx6acnz.fsf@mbork.pl> References: <87k0nfesns.fsf@zoho.eu> <87mtsbd31w.fsf@zoho.eu> <87a6oad81r.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="31198"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 28.0.50 Cc: help-gnu-emacs@gnu.org To: Stefan Monnier Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Mon May 31 22:10:29 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 1lnoF3-0007rr-L9 for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 31 May 2021 22:10:29 +0200 Original-Received: from localhost ([::1]:59698 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lnoF2-0000EY-KP for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 31 May 2021 16:10:28 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:53164) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lnoEB-00006a-Ga for help-gnu-emacs@gnu.org; Mon, 31 May 2021 16:09:35 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:59486) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lnoE6-0001Pv-TG for help-gnu-emacs@gnu.org; Mon, 31 May 2021 16:09:35 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id E7719E6B44; Mon, 31 May 2021 22:09:19 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mail.mojserwer.eu Original-Received: from mail.mojserwer.eu ([127.0.0.1]) by localhost (mail.mojserwer.eu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GEmHJGIAK2KS; Mon, 31 May 2021 22:09:07 +0200 (CEST) Original-Received: from localhost (178235147050.dynamic-3-poz-k-0-1-0.vectranet.pl [178.235.147.50]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 61665E61D9; Mon, 31 May 2021 22:09:06 +0200 (CEST) In-reply-to: Received-SPF: pass client-ip=195.110.48.8; envelope-from=mbork@mbork.pl; helo=mail.mojserwer.eu X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=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:130390 Archived-At: On 2021-05-31, at 21:47, Stefan Monnier via Users list for the GNU Emacs text editor wrote: >> Hm ... interesting. Yeah, maybe we should start do that more? > > Not really: it's better to avoid macros when you can. > But it's better to use macros than to use `eval`. > >> What kind of things or problems could or should you solve >> with macros? > > Whenever you find yourself forced to use `eval` ? Or when you lack some syntactical construct you could find useful, like anaphoric-if. Or if what you need is closer to a "special form" than to a function. A typical case is when you need a construct which will be able to evaluate something or not, depending on the circumstances. Or when you need a construct which will evaluate some form(s) /after/ doing something (remember that when a function gets its arguments, they are all evaluated before even the first form of a function is evaluated!). Here (shameless plug!) is an example of something you couldn't achieve with functions alone (unless you wanted to wrap some code in `(lambda () ...)', which would be rather ugly): http://mbork.pl/2016-04-24_The_conditional-save-excursion_macro Hth, -- Marcin Borkowski http://mbork.pl