From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: fgallina@gnu.org (=?utf-8?Q?Fabi=C3=A1n?= Ezequiel Gallina) Newsgroups: gmane.emacs.devel Subject: Re: [Emacs-diffs] trunk r117592: Grab all Python process output before inferior-python-mode hooks. Date: Wed, 30 Jul 2014 23:30:27 -0300 Message-ID: <877g2up8e4.fsf@gnu.org> References: <87d2cp2nn5.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1406773855 32537 80.91.229.3 (31 Jul 2014 02:30:55 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 31 Jul 2014 02:30:55 +0000 (UTC) Cc: emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Jul 31 04:30:45 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XCg8j-0006QS-BN for ged-emacs-devel@m.gmane.org; Thu, 31 Jul 2014 04:30:45 +0200 Original-Received: from localhost ([::1]:53946 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XCg8i-0004qK-MO for ged-emacs-devel@m.gmane.org; Wed, 30 Jul 2014 22:30:44 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:37704) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XCg8b-0004lg-3A for emacs-devel@gnu.org; Wed, 30 Jul 2014 22:30:42 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XCg8V-0003WY-8T for emacs-devel@gnu.org; Wed, 30 Jul 2014 22:30:37 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:49332) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XCg8V-0003WL-6D for emacs-devel@gnu.org; Wed, 30 Jul 2014 22:30:31 -0400 Original-Received: from 222-99-245-190.fibertel.com.ar ([190.245.99.222]:46405 helo=localhost) by fencepost.gnu.org with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1XCg8U-0005XR-Ap; Wed, 30 Jul 2014 22:30:30 -0400 In-Reply-To: (Stefan Monnier's message of "Mon, 28 Jul 2014 19:21:12 -0400") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:4830:134:3::e X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:173305 Archived-At: Stefan Monnier writes: >>>> + ;; Ensure all the output is accepted before running any hooks. >>>> + (accept-process-output (get-buffer-process (current-buffer))) >>>> + (sit-for 0.1 t)) >>> Why do you need sit-for here? >> I just added a comment about it in revno 117605. >> ;; At this point, all process output should have been received, but >> ;; on GNU/Linux, calling `python-shell-internal-send-string' without >> ;; a running internal shell fails to grab output properly unless >> ;; this `sit-for' is in place. >> Sorry about that, I should have placed that comment before! > > Sounds like a workaround for a problem somewhere in Emacs. > Could you make a bug-report for it, ideally providing a simple > test case? So I think I finally understand what's going on: When Python starts up, it actually sends two things to stdout in separate calls. The first one is the banner and the second is the initial prompt. What it seems to be happening is that on the first accept-process-output call, the output that is grabbed is just the banner, leaving the prompt outside, and that's what the sit-for was actually "fixing". The truth is (I think) that sit-for should be another accept-process-output call. To exercise this, I wrote the following example. (let ((buffer (get-buffer-create "*accept-bug*"))) (with-current-buffer "*accept-bug*" (start-process "python" (current-buffer) "python" "-i") (let ((process (get-buffer-process (current-buffer)))) (set-process-query-on-exit-flag process nil) (message "Output (0)\n=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D\n%s\n\n" (buffer-substring-no-properties (point-min) (point-max))) (accept-process-output process) ; (a) (message "Output (1)\n=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D\n%s\n\n" (buffer-substring-no-properties (point-min) (point-max))) (accept-process-output process) ; (b) (message "Output (2)\n=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D\n%s\n\n" (buffer-substring-no-properties (point-min) (point-max))) (process-send-string=20 process (format "print ('a' * 16)\n")) (accept-process-output process) ; (c) (prog1 (let ((output (buffer-substring-no-properties (point-min) (point-max)))) (format "Output (3)\n=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D\n%s\n\n" output)) (kill-buffer (current-buffer)))))) Evaluating that should let you see in the *Messages* buffer the behavior I'm describing. Commenting any of the accept-process-output calls, ends up returning just the banner and the prompt sans the output from the print statement. My guess then is that this is not really an Emacs bug but rather a singularity of how the Python process sends its output, but since I'm no expert to tell if accept-process-output should be smart enough to handle that case, I would let you to decide. Saludos, Fabi=C3=A1n