Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!bcyclone02.am1.xlned.com!bcyclone02.am1.xlned.com!newsfeed.xs4all.nl!newsfeed1.news.xs4all.nl!xs4all!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 0.046 X-Spam-Evidence: '*H*': 0.91; '*S*': 0.00; 'args': 0.07; 'subject:code': 0.07; 'dan': 0.09; 'lawrence': 0.09; 'worse': 0.09; 'def': 0.12; 'chunks': 0.16; 'it;': 0.16; 'iterates': 0.16; 'itertools': 0.16; 'itself,': 0.16; 'recipe': 0.16; 'work."': 0.16; 'weird': 0.16; 'wrote:': 0.18; 'wed,': 0.18; '(the': 0.22; "i've": 0.25; 'header:In-Reply-To:1': 0.27; 'function': 0.29; 'url:bugs': 0.29; 'points': 0.29; 'message-id:@mail.gmail.com': 0.30; "i'm": 0.30; 'code': 0.31; 'relies': 0.31; 'says': 0.33; 'url:python': 0.33; 'but': 0.35; 'received:google.com': 0.35; 'subject:?': 0.36; 'url:org': 0.36; 'detail': 0.37; 'url:library': 0.38; 'skip:[ 10': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'to:addr:python.org': 0.39; 'according': 0.40; 'url:3': 0.61; 'guarantee': 0.63; 'zip': 0.64; 'mar': 0.68; 'fact,': 0.69; 'url:4': 0.69; 'opinions': 0.70; 'article': 0.77; '"it': 0.84; '2015': 0.84; 'abc': 0.84; 'guaranteed.': 0.84; 'url:posts': 0.84; 'sitting': 0.91 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=wtYyWgm7fjdaWlXBfT9k9/cTw26O47Jxc+juiPKWycU=; b=xlAL5jc/3TNWuVXTTpweOxTktZ216IqYtqjUDBbgMvHlwZ5d/YQ5yaqTAEDG0Ex7DM t7aEwFnQlnE36UKHPeJ4Sk1x0b2AMxhkub+pujumFnM9m6Yi8+0hGYNUxHebP5ce7dDR A6jqwbef5zb/1SfHFam69cv3wnHNAjEKDw04XBdlA505BA/sk1/oXX3kJ1uORaM+oQdJ 4DNfuxKnxQd9eUutMo0TFeeQYxvio1zD7v3z5jMZZ0LkB/vbGlC2hFIUsPIAEvAj4D3/ meD2sf9A0L94Yj4wf2oESQu1b/cICBGHx7bSVJT7nLJWoFC6jkzhwxuzw8PGbVjkwPHN oiyg== X-Received: by 10.66.161.161 with SMTP id xt1mr163705679pab.35.1426690840143; Wed, 18 Mar 2015 08:00:40 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Ian Kelly Date: Wed, 18 Mar 2015 08:59:59 -0600 Subject: Re: Brilliant or insane code? To: Python Content-Type: text/plain; charset=UTF-8 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.19 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: 29 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1426690849 news.xs4all.nl 2893 [2001:888:2000:d::a6]:34265 X-Complaints-To: abuse@xs4all.nl X-Received-Bytes: 4413 X-Received-Body-CRC: 1349568080 Xref: csiph.com comp.lang.python:87683 On Tue, Mar 17, 2015 at 7:14 PM, Dan Sommers wrote: > On Wed, 18 Mar 2015 00:35:42 +0000, Mark Lawrence wrote: > >> I've just come across this >> http://www.stavros.io/posts/brilliant-or-insane-code/ as a result of >> this http://bugs.python.org/issue23695 >> >> Any and all opinions welcomed, I'm chickening out and sitting firmly >> on the fence. > > According to the article itself, "it relies in an implementation detail > (the order the zip function iterates over the arrays) to work." Then > again, the article also points to the official docs that says that this > implementation detail is guaranteed. > > So it's no worse than depending on some weird but *documented* corner of > the IEEE-754 or POSIX spec. In fact, this is also a code recipe found in the itertools documentation. The official docs don't just guarantee it; they *recommend* it. def grouper(iterable, n, fillvalue=None): "Collect data into fixed-length chunks or blocks" # grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx" args = [iter(iterable)] * n return zip_longest(*args, fillvalue=fillvalue) https://docs.python.org/3.4/library/itertools.html