Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!feeder.news-service.com!xlned.com!feeder5.xlned.com!newsfeed.xs4all.nl!newsfeed6.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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'plenty': 0.03; 'warnings': 0.05; 'builtins': 0.07; 'subject:when': 0.07; 'python': 0.08; 'builtin': 0.09; 'from:addr:ethan': 0.09; 'from:addr:stoneleaf.us': 0.09; 'from:name:ethan furman': 0.09; 'highlight': 0.09; 'message-id:@stoneleaf.us': 0.09; 'received:gator410.hostgator.com': 0.09; '~ethan~': 0.09; 'examples': 0.11; 'am,': 0.12; 'library': 0.15; '16,': 0.15; 'grep': 0.16; 'highlighting': 0.16; 'n00bs': 0.16; 'received:72.11': 0.16; 'received:72.11.125': 0.16; 'received:72.11.125.166': 0.16; 'semanchuk': 0.16; 'subject:builtin': 0.16; 'such.': 0.16; 'sure,': 0.16; 'wrote:': 0.16; 'to:name:python-list': 0.18; 'seems': 0.20; 'detect': 0.21; 'header:In-Reply-To:1': 0.22; 'int,': 0.23; 'somehow': 0.23; 'variable': 0.24; 'there.': 0.24; 'aug': 0.24; 'times,': 0.24; 'do,': 0.25; 'code': 0.25; "i'm": 0.27; 'somebody': 0.28; 'all,': 0.28; 'raise': 0.28; 'problem': 0.28; 'looks': 0.29; 'times.': 0.30; 'harm': 0.30; 'str': 0.30; 'subject:?': 0.31; 'cases': 0.32; 'source': 0.33; "isn't": 0.33; 'sort': 0.33; 'actually': 0.33; 'probably': 0.33; "can't": 0.33; 'to:addr:python-list': 0.33; 'done': 0.34; 'header:User-Agent:1': 0.34; 'yourself.': 0.34; 'things': 0.34; 'all.': 0.34; 'trouble': 0.35; 'file': 0.36; 'issue': 0.36; 'using': 0.37; 'but': 0.37; 'something': 0.37; 'open': 0.37; 'could': 0.38; 'think': 0.38; 'strong': 0.38; 'steven': 0.38; 'subject:: ': 0.39; 'either': 0.39; "there's": 0.39; 'to:addr:python.org': 0.39; 'might': 0.40; "it's": 0.40; 'where': 0.40; 'more': 0.60; 'hope': 0.61; 'further': 0.64; 'received:websitewelcome.com': 0.64; 'cost': 0.65; 'received:184': 0.67; 'anything,': 0.73; 'protecting': 0.73; 'average': 0.77; 'bitten': 0.84; 'contributors': 0.84; 'warning.': 0.84; 'dozens': 0.91 Date: Tue, 16 Aug 2011 08:41:08 -0700 From: Ethan Furman User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 To: python-list Subject: Re: Why no warnings when re-assigning builtin names? References: <4e49c89a$0$30001$c3e8da3$5496439d@news.astraweb.com> <4e49fcd7$0$29974$c3e8da3$5496439d@news.astraweb.com> <2A3EB048-1F10-46E8-973F-9BBD303E7B9F@semanchuk.com> In-Reply-To: <2A3EB048-1F10-46E8-973F-9BBD303E7B9F@semanchuk.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator410.hostgator.com X-AntiAbuse: Original Domain - python.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - stoneleaf.us X-BWhitelist: no X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: mail.admailinc.com ([192.168.10.136]) [72.11.125.166]:3747 X-Source-Auth: ethan+stoneleaf.us X-Email-Count: 2 X-Source-Cap: dG9idWs7dG9idWs7Z2F0b3I0MTAuaG9zdGdhdG9yLmNvbQ== X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 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: 47 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1313508227 news.xs4all.nl 23915 [2001:888:2000:d::a6]:59259 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:11564 Philip Semanchuk wrote: > On Aug 16, 2011, at 1:15 AM, Steven D'Aprano wrote: >> Protecting n00bs from their own errors is an admirable aim, but have you >> considered that warnings for something which may be harmless could do more >> harm than good? > > Isn't the whole point of a warning to highlight behavior that's not strictly > wrong but looks iffy? Sort of, "I can't be sure, but this looks like trouble > to me. I hope you know what you're doing". If we are to eschew warnings in > cases where they might be highlighting something harmless, then we would > have no warnings at all. Sounds good to me. ;) Keep such things in the IDE's, and then those who desire such behavior can have it there. Do not clutter Python with such. >> Perhaps. But I'm not so sure it is worth the cost of extra code to detect >> shadowing and raise a warning. After all, the average coder probably never >> shadows anything, > > One need look no further than the standard library to see a strong > counterexample. grep through the Python source for " file =". I see dozens > of examples of this builtin being used as a common variable name. I would > call contributors to the standard library above-average coders, and we can > see them unintentionally shadowing builtins many times. What makes you think it's unintentional? file makes a good variable name, and if you don't need it to actually open a file there's nothing wrong with using it yourself. >> and for those that do, once they get bitten *once* they >> either never do it again or learn how to shadow safely. > > I have done it plenty of times, never been bitten (thankfully) and still > do it by accident now and again. Seems to me the real issue is somebody using a builtin, such as str or int, and that they somehow manage to do this without realizing, "wait a sec', that's one of my variables!" I don't see that as a problem that Python needs to solve. ~Ethan~