Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.023 X-Spam-Evidence: '*H*': 0.96; '*S*': 0.00; 'interpreter': 0.05; 'detect': 0.07; 'python': 0.11; "wouldn't": 0.14; 'changes': 0.15; 'benjamin': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; "guido's": 0.16; 'porting': 0.16; 'subject:python3': 0.16; 'wrote:': 0.18; 'thu,': 0.19; 'seems': 0.21; 'machine': 0.22; 'aug': 0.22; 'integer': 0.24; 'source': 0.25; 'header:In-Reply-To:1': 0.27; 'am,': 0.29; 'errors': 0.30; 'mode': 0.30; 'message-id:@mail.gmail.com': 0.30; 'code': 0.31; 'division': 0.31; 'run': 0.32; 'another': 0.32; 'received:google.com': 0.35; 'to:addr:python-list': 0.38; 'to:addr:python.org': 0.39; 'problems.': 0.60; 'most': 0.60; 'august': 0.61; 'such': 0.63; 'wish': 0.70; 'joke,': 0.84; 'oscar': 0.84; 'silent': 0.95; '2013': 0.98 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=Yui8R3XFocrnV1D8JJdFKHREa7BF9c8mvkZAYwc0Dg4=; b=oU9DkuUPcVcVIVr1GM+rI7JXU5LsE2r4RNzCY1vSbBUsz9KcC+qjuQB71la1cjS1ei EqYaGNVRw6fC8I6eyS2s+mevYj74ddwyXcwnvh5dTi1TMbBPnZ3Y+VC/o3jtclacmRfJ BpsJhFh61+YdwmIz0dOv2mTvzxl7OYhEvQl+cpkuxIC/YiIOaarcp5/gSXVfANSvkMyV VPcAoah22Lr4ekKaddAylNxNkxWltCqjwJW/+Q/m+BdfJwobrG60e0HJm3aIRUuCF31/ 3IDJsdzGK9AIFY0liz3lYnG5zIU8TTo9NYG8TN0yn/+tPERlsm9kK7aJriVFTxvyS1Lk Sotg== MIME-Version: 1.0 X-Received: by 10.52.166.71 with SMTP id ze7mr93956vdb.50.1377703607533; Wed, 28 Aug 2013 08:26:47 -0700 (PDT) In-Reply-To: References: Date: Thu, 29 Aug 2013 01:26:47 +1000 Subject: Re: python3 integer division debugging From: Chris Angelico To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 18 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1377703609 news.xs4all.nl 15971 [2001:888:2000:d::a6]:56624 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:53167 On Thu, Aug 29, 2013 at 1:21 AM, Oscar Benjamin wrote: > On 28 August 2013 16:15, Neal Becker wrote: >> The change in integer division seems to be the most insidious source of silent >> errors in porting code from python2 - since it changes the behaviour or valid >> code silently. >> >> I wish the interpreter had an instrumented mode to detect and report such >> problems. > > Is that a joke? > > Run the code under Python 2.6/2.7 with the -3 flag: I wouldn't say that's a joke, it's just another demonstration of Guido's time machine :) ChrisA