From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: please review new branch feature/byte-unwind-protect Date: Sat, 27 Jan 2018 16:28:46 -0500 Message-ID: References: <87inbtnobf.fsf@tromey.com> <87h8r719us.fsf@metalevel.at> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1517088514 32756 195.159.176.226 (27 Jan 2018 21:28:34 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 27 Jan 2018 21:28:34 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Jan 27 22:28:29 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 1efY1P-0007u3-Em for ged-emacs-devel@m.gmane.org; Sat, 27 Jan 2018 22:28:23 +0100 Original-Received: from localhost ([::1]:45593 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1efY3Q-0004V8-8C for ged-emacs-devel@m.gmane.org; Sat, 27 Jan 2018 16:30:28 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:39623) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1efY2h-0004Uv-Ul for emacs-devel@gnu.org; Sat, 27 Jan 2018 16:29:44 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1efY2e-000606-Pw for emacs-devel@gnu.org; Sat, 27 Jan 2018 16:29:43 -0500 Original-Received: from [195.159.176.226] (port=59074 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1efY2e-0005y2-Id for emacs-devel@gnu.org; Sat, 27 Jan 2018 16:29:40 -0500 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1efY0J-0003yC-3r for emacs-devel@gnu.org; Sat, 27 Jan 2018 22:27:15 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 17 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:edMSAV3w6ETyPqoNe5JP6lIWhzU= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 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:222267 Archived-At: > I have one feature request that is related to unwind-protect, filed as > issue #23963: While we're here I have another related feature request: make it possible to provide a "rewind". Currently the C code has a few hard-coded rewinds (basically: those for let bindings and those for save-excursion, IIRC), but doesn't offer any way to provide one's own. The rewinds are used in the backtrace debugger when the user evaluates an expression with `e` (which evaluates the expression in the specific stack frame at point, so it first unwinds up to that stack frame so that the evaluation has access to the same variables in the same buffer, and afterwards rewinds back down to the stack frame where the error occurred). Stefan