From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Edebug corrupting point in buffers; we need buffer-point and set-buffer-point, perhaps. Date: Mon, 31 Oct 2022 20:46:12 +0000 Message-ID: References: <83v8o0dtg3.fsf@gnu.org> <83pme8dp2r.fsf@gnu.org> <83mt9bev37.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="35384"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Oct 31 21:47:10 2022 Return-path: Envelope-to: ged-emacs-devel@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 1opbgb-0008yk-1g for ged-emacs-devel@m.gmane-mx.org; Mon, 31 Oct 2022 21:47:09 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1opbfs-0000lh-76; Mon, 31 Oct 2022 16:46:24 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1opbfm-0000lI-7O for emacs-devel@gnu.org; Mon, 31 Oct 2022 16:46:18 -0400 Original-Received: from mx3.muc.de ([193.149.48.5]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1opbfk-0003q8-5s for emacs-devel@gnu.org; Mon, 31 Oct 2022 16:46:18 -0400 Original-Received: (qmail 91322 invoked by uid 3782); 31 Oct 2022 21:46:13 +0100 Original-Received: from acm.muc.de (p4fe15da4.dip0.t-ipconnect.de [79.225.93.164]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Mon, 31 Oct 2022 21:46:12 +0100 Original-Received: (qmail 20224 invoked by uid 1000); 31 Oct 2022 20:46:12 -0000 Content-Disposition: inline In-Reply-To: <83mt9bev37.fsf@gnu.org> X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.5; envelope-from=acm@muc.de; helo=mx3.muc.de 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_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: "Emacs-devel" Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:298890 Archived-At: Hello, Eli. On Mon, Oct 31, 2022 at 19:55:40 +0200, Eli Zaretskii wrote: > > Date: Mon, 31 Oct 2022 15:46:07 +0000 > > Cc: emacs-devel@gnu.org > > From: Alan Mackenzie > > > I'm not sure performance in a debugger is a reason good enough to add > > > 2 more primitives. The fact that we didn't need them until now should > > > tell us something, no? > > Well, I timed it. With 207 buffers, creating an alist of (buffer . > > buffere-point) with my new function was 17 times as fast as using > > with-current-buffer and point. > 17 times faster doesn't yet tell how important is the speedup, because > you give no absolute numbers, and they are what's important here. I think I did. To quote: > > It's probably moot, though, since the "slow" restoration only took > > 0.00137 seconds for all 207 buffers. > > But on the other hand, these two functions feel like they ought to exist. > > They could save a lot of clumsy programming with swapping the buffer, > > just to get or set point. > There's nothing clumsy with what we did, and the fact that we did > manage without them speaks volumes. OK. > > > > +DEFUN ("buffer-point", Fbuffer_point, Sbuffer_point, 1, 1, 0, > > > > + doc: /* Return the buffer point of BUFFER-OR-NAME. > > > > +The argument may be a buffer or the name of an existing buffer. */) > > > > + (Lisp_Object buffer_or_name) > > > Why not an optional argument to 'point'? And why in buffer.c and not > > > in editfns.c? > > I'm not sure what you mean by an optional argument, here. > I mean (point &optional buffer), of course, what else could I mean? OK. > > > > + return (make_fixnum (b->pt)); > > > Please never-ever use b->pt etc. directly. We have BUF_PT and other > > > macros for that, and for a good reason. > > BUF_PT and friends work specifically on current_buffer. > No, they don't: Apologies. I got that wrong. > /* Position of point in buffer. */ > INLINE ptrdiff_t > BUF_PT (struct buffer *buf) > { > return (buf == current_buffer ? PT > : NILP (BVAR (buf, pt_marker)) ? buf->pt > : marker_position (BVAR (buf, pt_marker))); > } > > The whole idea of the new functions is to avoid having to switch > > buffers. > We do this from C in a gazillion of places. OK. I now think these new functions aren't really needed, mainly because the current way, though much slower, is fast enough. I still think they would be a neater way of getting/setting a buffer point, but it's not a big thing. -- Alan Mackenzie (Nuremberg, Germany).