Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!feeder.news-service.com!feeder.news-service.com!newsfeed.xs4all.nl!newsfeed5.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; 'assign': 0.04; 'instance': 0.05; 'warnings': 0.05; 'builtins': 0.07; 'compiler': 0.07; 'differently.': 0.07; 'interpreter': 0.07; 'names.': 0.07; 'subject:when': 0.07; 'suggesting': 0.07; 'variable,': 0.07; 'python': 0.08; '__future__': 0.09; 'eclipse': 0.09; 'overwrite': 0.09; 'folks': 0.15; 'result,': 0.15; '"from': 0.16; '(eg.': 0.16; 'keyword,': 0.16; 'received:mindspring.com': 0.16; 'subject:builtin': 0.16; 'surprising': 0.16; 'x-mailer:apple mail (2.1084)': 0.16; 'syntax': 0.16; 'wrote:': 0.16; 'language': 0.17; 'later': 0.21; "doesn't": 0.22; 'header:In-Reply-To:1': 0.22; 'pm,': 0.24; 'aug': 0.24; 'code.': 0.26; 'helpful': 0.26; "i'm": 0.27; 'import': 0.28; 'anyway.': 0.29; 'explicitly': 0.29; 'fairly': 0.30; 'accidentally': 0.30; "they'll": 0.30; 'class': 0.30; 'subject:?': 0.31; 'seem': 0.31; 'list': 0.32; 'received:24': 0.32; 'actual': 0.32; 'break': 0.32; 'agree': 0.33; 'it.': 0.33; 'actually': 0.33; 'to:addr:python-list': 0.33; 'that,': 0.33; 'project': 0.34; 'weird': 0.34; 'charset:us-ascii': 0.36; 'problem.': 0.36; 'skip:" 10': 0.36; 'example,': 0.37; 'class.': 0.37; 'but': 0.37; 'something': 0.37; 'could': 0.38; 'think': 0.38; 'some': 0.38; 'should': 0.38; 'subject:: ': 0.39; 'difficult': 0.39; 'enough': 0.39; 'help': 0.39; 'header:Mime- Version:1': 0.39; 'user': 0.39; "there's": 0.39; 'to:addr:python.org': 0.39; 'might': 0.40; "it's": 0.40; 'header :Message-Id:1': 0.61; 'postings': 0.64; 'cause': 0.67; 'receive': 0.67; 'often.': 0.84; 'received:69.73': 0.84; 'regard.': 0.84; 'regularity,': 0.84; 'warning.': 0.84 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Apple Message framework v1084) Subject: Re: Why no warnings when re-assigning builtin names? From: Philip Semanchuk In-Reply-To: Date: Mon, 15 Aug 2011 18:13:02 -0400 Content-Transfer-Encoding: quoted-printable References: To: Lista-Comp-Lang-Python list X-Mailer: Apple Mail (2.1084) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - deimos.nocdirect.com X-AntiAbuse: Original Domain - python.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - semanchuk.com 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: 42 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1313446389 news.xs4all.nl 23886 [2001:888:2000:d::a6]:34747 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:11475 On Aug 15, 2011, at 5:52 PM, Gerrat Rickert wrote: > With surprising regularity, I see program postings (eg. on > StackOverflow) from inexperienced Python users accidentally > re-assigning built-in names. >=20 >=20 >=20 > For example, they'll innocently call some variable, "list", and assign = a > list of items to it. >=20 > ...and if they're _unlucky_ enough, their program may actually work > (encouraging them to re-use this name in other programs). Or they'll assign a class instance to 'object', only to cause weird = errors later when they use it as a base class. I agree that this is a problem. The folks on my project who are new-ish = to Python overwrite builtins fairly often. Since there's never been any = consequence other than my my vague warnings that something bad might = happen as a result, it's difficult for them to develop good habits in = this regard. It doesn't help that Eclipse (their editor of choice) = doesn't seem to provide a way of coloring builtins differently. (That's = what I'm told, anyway. I don't use it.) > If they try to use an actual keyword, both the interpreter and = compiler > are helpful enough to give them a syntax error, but I think the = builtins > should be "pseudo-reserved", and a user should explicitly have to do > something *extra* to not receive a warning. Unfortunately you're suggesting a change to the language which could = break existing code. I could see a use for "from __future__ import = squawk_if_i_reassign_a_builtin" or something like that, but the current = default behavior has to remain as it is. JMO, Philip