Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed4.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 0.021 X-Spam-Evidence: '*H*': 0.96; '*S*': 0.00; 'below).': 0.09; 'exception.': 0.09; 'inherited': 0.09; 'pep': 0.09; 'python': 0.11; '2.7?': 0.16; 'from:addr:cs': 0.16; 'from:addr:zip.com.au': 0.16; 'from:name:cameron simpson': 0.16; 'hierarchy': 0.16; 'hmm.': 0.16; 'message-id:@cskk.homeip.net': 0.16; 'pathological': 0.16; 'simplicity,': 0.16; 'simpson': 0.16; 'url:peps': 0.16; 'exception': 0.16; 'wrote:': 0.18; '3.0': 0.19; 'pointed': 0.19; 'to:name:python-list@python.org': 0.22; 'header:User-Agent:1': 0.23; 'url:dev': 0.24; 'cheers,': 0.24; '(see': 0.26; 'possibly': 0.26; 'header:In-Reply-To:1': 0.27; 'leave': 0.29; 'raise': 0.29; '[2]': 0.30; 'statement': 0.30; 'catching': 0.31; "d'aprano": 0.31; 'exceptions': 0.31; 'steven': 0.31; 'probably': 0.32; 'me?': 0.32; 'interface': 0.32; 'url:python': 0.33; "i'd": 0.34; 'could': 0.34; 'subject:with': 0.35; 'basic': 0.35; 'board': 0.35; 'good.': 0.35; 'but': 0.35; 'there': 0.35; 'skip:> 10': 0.36; 'transition': 0.36; 'charset:us-ascii': 0.36; 'url:org': 0.36; 'starting': 0.37; 'to:addr:python-list': 0.38; 'expect': 0.39; 'does': 0.39; 'itself': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.39; 'changed': 0.39; 'even': 0.60; 'new': 0.61; 'content- disposition:inline': 0.62; 'great': 0.65; 'occur': 0.65; 'within': 0.65; 'iron': 0.68; 'stated': 0.69; 'enforced': 0.84; 'received:192.168.15': 0.84; 'subject:..': 0.84; 'adrian': 0.91; 'cause,': 0.91 Date: Sun, 12 Apr 2015 16:41:23 +1000 From: Cameron Simpson To: "python-list@python.org" Subject: Re: try..except with empty exceptions MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20150412063339.GA16977@cskk.homeip.net> User-Agent: Mutt/1.5.23 (2014-03-12) References: <20150412063339.GA16977@cskk.homeip.net> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.20 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: 28 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1428820887 news.xs4all.nl 2914 [2001:888:2000:d::a6]:41412 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:88859 On 12Apr2015 16:33, Cameron Simpson wrote: >Finally, if we were to expunge support for "except:", one would also need a >cast iron guarrentee that no exception could possibly occur which was not a >subclass of BaseException. I'd expect that to mean that "raise" of a >non-instance of BaseException to itself raise a TypeError. And I see that Steven D'Aprano has already pointed out PEP 352: http://www.python.org/dev/peps/pep-0352/ which is marked "Status: Final". It says: The raise statement will be changed to require that any object passed to it must inherit from BaseException. This will make sure that all exceptions fall within a single hierarchy that is anchored at BaseException [2] . This also guarantees a basic interface that is inherited from BaseException. The change to raise will be enforced starting in Python 3.0 (see the Transition Plan below). Hmm. Not in 2.7? I can see the breakage it could cause, but where does that leave me? I think I could probably move to catching Exception almost across the board even in 2.5+ and feel pretty good. Cheers, Cameron Simpson If your new theorem can be stated with great simplicity, then there will exist a pathological exception. - Adrian Mathesis