From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Lisp primitives and their calling of the change hooks Date: Fri, 5 Jan 2018 13:34:48 +0000 Message-ID: <20180105133448.GB6954@ACM> References: <20180103124543.GA5435@ACM> <20180104155111.GB6846@ACM> <20180104211154.GC6846@ACM> <838tdcbxrb.fsf@gnu.org> <20180105114107.GA6954@ACM> <83373kbguy.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: blaine.gmane.org 1515159442 26016 195.159.176.226 (5 Jan 2018 13:37:22 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 5 Jan 2018 13:37:22 +0000 (UTC) User-Agent: Mutt/1.7.2 (2016-11-26) Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jan 05 14:37:18 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eXSBR-0006Nz-DG for ged-emacs-devel@m.gmane.org; Fri, 05 Jan 2018 14:37:17 +0100 Original-Received: from localhost ([::1]:40545 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eXSDP-0007ZU-1e for ged-emacs-devel@m.gmane.org; Fri, 05 Jan 2018 08:39:19 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:60769) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eXSDG-0007Xu-4f for emacs-devel@gnu.org; Fri, 05 Jan 2018 08:39:11 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eXSDB-0007fB-9A for emacs-devel@gnu.org; Fri, 05 Jan 2018 08:39:10 -0500 Original-Received: from colin.muc.de ([193.149.48.1]:60255 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1eXSDB-0007ec-1c for emacs-devel@gnu.org; Fri, 05 Jan 2018 08:39:05 -0500 Original-Received: (qmail 70117 invoked by uid 3782); 5 Jan 2018 13:39:04 -0000 Original-Received: from acm.muc.de (p548C703C.dip0.t-ipconnect.de [84.140.112.60]) by colin.muc.de (tmda-ofmipd) with ESMTP; Fri, 05 Jan 2018 14:39:02 +0100 Original-Received: (qmail 7906 invoked by uid 1000); 5 Jan 2018 13:34:48 -0000 Content-Disposition: inline In-Reply-To: <83373kbguy.fsf@gnu.org> X-Delivery-Agent: TMDA/1.1.12 (Macallan) X-Primary-Address: acm@muc.de X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x [fuzzy] X-Received-From: 193.149.48.1 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:221615 Archived-At: Hello, Eli. On Fri, Jan 05, 2018 at 15:00:21 +0200, Eli Zaretskii wrote: > > Date: Fri, 5 Jan 2018 11:41:07 +0000 > > Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org > > From: Alan Mackenzie > > The "complex primitive" case can be distinguised from the "atomic > > primitive" case because either the call to `after-change-functions' > > is missing (i.e. there are two consecutive calls to > > `before-change-functions'), or in the first call to > > `after-change-functions', `OLD-LEN' is less then `END' - `BEG' in > > `before-change-functions'. > > The above leaves unsaid what happens when a "complex primitive" happens > > to call b-c-f and a-c-f as though it were an "atomic primitive". > It also provides no way to know, up front, whether a given primitive > I'm about to call, is one or the other. IMO, we need some way of > doing that, if we want to document this distinction. Do we really need this level of detail? My idea was to enable users of b-c-f and a-c-f to predict what they're going to be being hit with. There are two patterns of handling b/a-c-f, the "atomic" and the "complex". My above proposal documents enough for somebody using b/a-c-f to be able to handle the "atomic" and "complex" uses. Why does that hacker need to know exactly what each buffer-changing primitive does, or which falls into which category? Surely it is enough that she handle the b/a-c-f calls appropriately. What am I missing here? -- Alan Mackenzie (Nuremberg, Germany).