Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!newsfeed.xs4all.nl!newsfeed1.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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'broken': 0.04; 'cpython': 0.05; '"as': 0.07; 'fixes': 0.07; 'incompatible': 0.07; 'modify': 0.07; 'subject:support': 0.07; 'tom': 0.07; "ain't": 0.09; 'alter': 0.09; 'bug.': 0.09; 'created,': 0.09; 'dependency': 0.09; 'happen.': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'semantic': 0.09; 'subject:module': 0.09; 'subject:number': 0.09; 'subject:version': 0.09; 'used.': 0.09; 'api': 0.11; 'python': 0.11; 'bug': 0.12; 'jan': 0.12; 'backwards': 0.16; 'corrects': 0.16; 'fixes.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'reliably': 0.16; 'semantically': 0.16; 'demonstrate': 0.16; 'fix': 0.17; 'wrote:': 0.18; 'library': 0.18; 'dependent': 0.19; 'example': 0.22; 'header :User-Agent:1': 0.23; 'faq': 0.24; 'specifies': 0.24; 'specify': 0.24; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'patch': 0.29; '(which': 0.31; 'code': 0.31; 'accidentally': 0.31; 'author,': 0.31; 'minor': 0.31; 'safely': 0.31; 'probably': 0.32; 'compatible': 0.32; 'know.': 0.32; 'says': 0.33; 'alone': 0.33; 'problem': 0.35; 'except': 0.35; 'problem.': 0.35; 'equal': 0.35; 'but': 0.35; 'there': 0.35; 'version': 0.36; 'url:org': 0.36; 'depends': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'does': 0.39; 'realize': 0.39; 'supporting': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'called': 0.40; 'users': 0.40; 'release': 0.40; 'how': 0.40; 'even': 0.60; 'skip:u 10': 0.60; 'future': 0.60; 'break': 0.61; 'introduced': 0.61; 'new': 0.61; 'numbers': 0.61; 'received:173': 0.61; 'simple': 0.61; 'first': 0.61; "you've": 0.63; 'such': 0.63; 'soon': 0.63; 'become': 0.64; 'management': 0.65; 'situation': 0.65; 'compliant': 0.68; 'past.': 0.68; 'safe': 0.72; 'inform': 0.78; 'received:fios.verizon.net': 0.84; 'restores': 0.84; 'unacceptable': 0.84; 'good,': 0.91; 'officially': 0.91; 'releases.': 0.91 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: module version number support for semver.org Date: Thu, 10 Apr 2014 19:34:29 -0400 References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Gmane-NNTP-Posting-Host: pool-173-75-254-207.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 In-Reply-To: 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: 58 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1397172900 news.xs4all.nl 2897 [2001:888:2000:d::a6]:54862 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:70073 On 4/10/2014 6:45 PM, J=C3=B6rn Hees wrote: > what do you think about officially supporting Semantic Versioning? > (http://semver.org ) It is a nice fantasy. Under "Why...?" the author, Tom Preston-Werner, says "A simple example will demonstrate how Semantic Versioning can make=20 dependency hell a thing of the past. Consider a library called=20 "Firetruck." It requires a Semantically Versioned package named=20 "Ladder." At the time that Firetruck is created, Ladder is at version=20 3.1.0. Since Firetruck uses some functionality that was first introduced = in 3.1.0, you can safely specify the Ladder dependency as greater than=20 or equal to 3.1.0 but less than 4.0.0. Now, when Ladder version 3.1.1=20 and 3.2.0 become available, you can release them to your package=20 management system and know that they will be compatible with existing=20 dependent software." Except you cannot know. Even though Firetruck works with Ladder 3.1.0,=20 one *cannot* know for sure that is will work with Ladder 3.1.1, let=20 alone 3.2.0. 1. Python use patch (micro, .z) numbers for bug fixes. Tom specifies=20 "backwards compatible bug fixes". There ain't no such thing. Bug fixes=20 break code that depends on the bug. Such dependence may be unintentional = and not known until a supposedly safe patch release breaks the code that = uses it. 2. Accidents, including regressions, happen. In respone to FAQ "What do=20 I do if I accidentally release a backwards incompatible change as a=20 minor version?" (which probably happends with every x.y.0 CPython=20 release), Tom says "As soon as you realize that you've broken the Semantic Versioning spec, = fix the problem and release a new minor version that corrects the=20 problem and restores backwards compatibility. Even under this=20 circumstance, it is unacceptable to modify versioned releases. If it's=20 appropriate, document the offending version and inform your users of the = problem so that they are aware of the offending version." This is well and good, but it invalidates the claim that one can=20 reliably depend and mechanically base action on future release numbers.=20 The answer to "What if I inadvertently alter the public API in a way=20 that is not compliant with the version number change?" has the same probl= em. This is not to say that Semver does not improve the situation when it=20 can be used. --=20 Terry Jan Reedy