From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Daniel Colascione Newsgroups: gmane.emacs.devel Subject: Re: Unbalanced change hooks (part 2) [Documentation fix still remaining] Date: Tue, 30 Aug 2016 10:46:44 -0700 Message-ID: <67e1e007-c944-b91e-6c4b-b06b51beddc1@dancol.org> References: <20160811112951.GA2154@acm.fritz.box> <7e1478b6-cf00-fcbf-8c24-43bdaa57e2b6@dancol.org> <415d1cca-f32c-624e-a4be-9aadcf8a0f17@dancol.org> <83inujbpek.fsf@gnu.org> <20160830171222.GA6672@acm.fritz.box> <5857ab7e-e85c-c6ae-ba1a-b1337ae57f2c@dancol.org> <83fupmm9ul.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1472579259 21812 195.159.176.226 (30 Aug 2016 17:47:39 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 30 Aug 2016 17:47:39 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 Cc: acm@muc.de, 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 Tue Aug 30 19:47:35 2016 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 1ben8I-0005Bg-Dq for ged-emacs-devel@m.gmane.org; Tue, 30 Aug 2016 19:47:34 +0200 Original-Received: from localhost ([::1]:50466 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ben8F-0001QK-Vz for ged-emacs-devel@m.gmane.org; Tue, 30 Aug 2016 13:47:32 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:53172) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ben7f-0001Q0-IN for emacs-devel@gnu.org; Tue, 30 Aug 2016 13:46:56 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ben7a-0005qh-HT for emacs-devel@gnu.org; Tue, 30 Aug 2016 13:46:54 -0400 Original-Received: from dancol.org ([2600:3c01::f03c:91ff:fedf:adf3]:54172) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ben7a-0005qV-56; Tue, 30 Aug 2016 13:46:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=dancol.org; s=x; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:Cc:References:To:Subject; bh=gbRI1yIMamub5naJApFcPznuX5VmMOyhTrEeQtYBPBQ=; b=H1NLFs70EaBW/GT7rNrYLuMF/DJRZCorIjpMm24oYqj6bYbMzNxDeBA3T4/AASMks9WLGSJ6E4SfWizg7gWZJjONmTgbqjarXFPFJRqDjguV7RUi5hf/IQc7ffEjqsGNnp7ZJJvBrAW9eSOSNTpuiWRb39b1a1fYtFSjuZWBbr5WfTC4MAbv5DfZ07I7h1mS3MZ7IhiLoL6nM5T3jfdsGITsmOkkNtsz3yv6udaKyH7JqB6Knh/ZlOtJIi3QzPYgXiGVyTIYxjhCeaUiAoUFpWkaHj7m7V2I35gBFCrVPr3Q3V6WTZpL4pQ43sq66s7zommpRVMJ0Ol4FrAG/wt4yA==; Original-Received: from c-73-97-199-232.hsd1.wa.comcast.net ([73.97.199.232] helo=[192.168.1.173]) by dancol.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1ben7X-0007Mz-OU; Tue, 30 Aug 2016 10:46:47 -0700 In-Reply-To: <83fupmm9ul.fsf@gnu.org> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2600:3c01::f03c:91ff:fedf:adf3 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:206979 Archived-At: On 08/30/2016 10:42 AM, Eli Zaretskii wrote: >> Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org >> From: Daniel Colascione >> Date: Tue, 30 Aug 2016 10:27:45 -0700 >> >> +The region given to each of these functions is a conservative >> +approximation of the region about to changed. After running the >> +before-change-functions, Emacs will make zero or more fine-grained >> +buffer changes and run after-change-functions for each. Do not expect >> +before-change-functions and after-change-functions to be called in >> +balanced pairs. > > The last sentence here is repeated afterwards, for no good reason. > (Also, the markup is missing, but that's just an aside.) I figured it was a good idea to highlight this fact directly in the variable documentation blob. I can add a "see below" link. > >> - Do @emph{not} expect the before-change hooks and the after-change >> -hooks be called in balanced pairs around each buffer change. Also >> -don't expect the before-change hooks to be called for every chunk of >> -text Emacs is about to delete. These hooks are provided on the >> -assumption that Lisp programs will use either before- or the >> -after-change hooks, but not both, and the boundaries of the region >> -where the changes happen might include more than just the actual >> -changed text, or even lump together several changes done piecemeal. >> + Do @emph{not} expect the before-change hooks and the after-change >> +hooks be called in balanced pairs around each buffer change. >> +The before-change-functions region is a conservative bound on the zero >> +or more fine-grained changes to follow. Emacs informs user code about >> +the actual changes to the buffer through calls to >> +after-change-functions; these fine-grained changes will always fall >> +inside the broad change region Emacs describes by calling >> +before-change-functions. > > You removed the part about text deletion, which is not specific to > revert-buffer, so that information is now lost. I don't want to lose > it. The text deletion part is a real and serious bug. As Stefan points out, it makes it impossible to use b-c-f to invalidate caches. > > Other than that, I don't see how your text is more accurate, it's just > a different wording dancing around the same issues trying to side-step > them by replacing one vague description by another. My proposed description highlights how the b-c-f region contains the a-c-f regions. I understand that you believe that the existing documentation communicates this fact, but I strongly disagree. The relationship between the b-c-f region and the a-c-f regions needs to be spelled out explicitly. > > If all you want is to remove this part: > > These hooks are provided on the assumption that Lisp programs will > use either before- or the after-change hooks, but not both > > then I don't necessarily mind, although I do believe it is true, and > the readers should be aware of that. I strongly disagree. b-c-f is a perfectly good way to invalidate caches.