From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.help Subject: Re: Too fine design granularity leads to numerous macro/function/command existed in Emacs. Date: Sat, 14 Aug 2021 09:18:41 +0300 Message-ID: <83o8a0blby.fsf@gnu.org> References: <838s15dcwl.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="1559"; mail-complaints-to="usenet@ciao.gmane.io" To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Aug 14 08:19:24 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 1mEn0t-0000A3-4K for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 14 Aug 2021 08:19:23 +0200 Original-Received: from localhost ([::1]:51726 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mEn0r-0006MG-NZ for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 14 Aug 2021 02:19:21 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:35128) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mEn0Q-0006Jt-50 for help-gnu-emacs@gnu.org; Sat, 14 Aug 2021 02:18:54 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:43496) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mEn0P-0003Hl-V6 for help-gnu-emacs@gnu.org; Sat, 14 Aug 2021 02:18:53 -0400 Original-Received: from 84.94.185.95.cable.012.net.il ([84.94.185.95]:3354 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mEn0P-0003LJ-Hp for help-gnu-emacs@gnu.org; Sat, 14 Aug 2021 02:18:53 -0400 In-Reply-To: (message from Hongyi Zhao on Sat, 14 Aug 2021 08:46:27 +0800) 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:132531 Archived-At: > From: Hongyi Zhao > Date: Sat, 14 Aug 2021 08:46:27 +0800 > Cc: help-gnu-emacs > > > Specifically about the one example you provided: directory-files is a > > primitive, written in C, so it provides the basic functionality of > > fetching file names from a single directory. The > > directory-files-recursively function is written in Lisp, it builds on > > that primitive and provides extended functionality. > > Thank you for letting me know this difference, which I really didn't > notice before. But there's still one question I don't understand: > C is a compiled language, so how does the compilation and invocation > of such C primitives work in Emacs? Are they compiled into libraries > and called in real time? The low-level infrastructure of the Lisp machine in Emacs is also written in C, and that includes the primitives used to call Lisp functions. Those primitives have a special way of calling other primitives written in C. Basically, a primitive written in C is wrapped in a special 'subr' object that tells Emacs about this, and then such primitives are called via the normal C mechanisms of calling functions. For more details, I suggest to study the node "Writing Emacs Primitives" in the ELisp manual.