Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!news.shlink.de!news1.wobline.de!news.bcc.de!newsfeeder.ewetel.de!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 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'sorts': 0.04; 'over,': 0.05; 'attribute': 0.07; 'exception,': 0.07; 'raised': 0.07; 'received:verizon.net': 0.07; 'terry': 0.07; 'python': 0.08; 'correct.': 0.09; 'exception.': 0.09; 'exceptions': 0.09; 'fix.': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:80.91.229.12': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'received:lo.gmane.org': 0.09; 'subclass': 0.09; 'throw': 0.09; 'subject:error': 0.10; 'exception': 0.12; '"exception': 0.16; 'errno': 0.16; 'reedy': 0.16; 'socket.error': 0.16; 'surprising': 0.16; 'towns': 0.16; 'unhandled': 0.16; 'wrote:': 0.16; '>>>': 0.18; 'jan': 0.19; "doesn't": 0.22; 'header :In-Reply-To:1': 0.22; '(or': 0.23; 'pm,': 0.24; 'libraries': 0.24; 'expect': 0.25; 'writes:': 0.25; "i'm": 0.27; 'host': 0.27; 'paul': 0.28; 'remote': 0.28; 'raise': 0.28; 'bugs': 0.28; 'mode': 0.28; 'operations': 0.30; 'bare': 0.30; 'down,': 0.30; 'fails,': 0.30; '(e.g.': 0.31; 'list': 0.32; 'there': 0.33; 'to:addr:python- list': 0.33; 'that,': 0.33; 'someone': 0.34; 'header:User- Agent:1': 0.34; 'approach.': 0.34; 'header:X-Complaints-To:1': 0.35; 'certain': 0.35; 'unless': 0.36; 'anything': 0.36; 'connection': 0.36; 'instead.': 0.37; 'but': 0.37; 'something': 0.37; 'received:org': 0.38; 'steven': 0.38; 'some': 0.38; 'should': 0.38; 'went': 0.38; 'subject:: ': 0.39; 'etc.)': 0.39; 'represent': 0.39; 'header:Mime-Version:1': 0.39; 'either': 0.39; 'subject:with': 0.39; "there's": 0.39; "couldn't": 0.39; 'recommended': 0.39; 'data': 0.39; 'to:addr:python.org': 0.39; 'case': 0.39; "it's": 0.40; 'minimum': 0.40; 'power': 0.63; 'customer': 0.65; 'ever': 0.65; 'cause': 0.67; 'site.': 0.68; 'dealing': 0.69; 'business': 0.70; 'kinds': 0.70; 'heavy': 0.71; 'failure': 0.73; 'retail': 0.77; 'cycling': 0.84; 'everything.': 0.84; 'irrelevant.': 0.84; 'mention.': 0.84; 'remedy': 0.84; 'subject:... ': 0.84; 'subject:types': 0.84; 'absolutely': 0.98 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: try... except with unknown error types Date: Sun, 21 Aug 2011 15:52:28 -0400 References: <4e4ec405$0$29994$c3e8da3$5496439d@news.astraweb.com> <7xipprsxha.fsf@ruckus.brouhaha.com> <4e5015ad$0$29986$c3e8da3$5496439d@news.astraweb.com> <7xty9ahb84.fsf@ruckus.brouhaha.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: pool-74-109-121-73.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0) Gecko/20110812 Thunderbird/6.0 In-Reply-To: <7xty9ahb84.fsf@ruckus.brouhaha.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: 39 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1313956388 news.xs4all.nl 23913 [2001:888:2000:d::a6]:55091 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:11959 On 8/21/2011 2:26 PM, Paul Rubin wrote: > Steven D'Aprano writes: >>> But there's no way to know what that minimum is. Python libraries throw >>> all sorts of exceptions that their documentation doesn't mention. >> >> Yes, you're absolutely correct. But it's also irrelevant. Most of those >> exceptions should not be caught, even if you know what they are, because >> they represent either bugs that should be fixed, or bad data which should >> raise an exception. A bare except, or except Exception, is hardly ever the >> right approach. > > I'm not sure what to do instead. The exceptions I'm currently dealing > with happen when certain network operations go wrong (e.g. network or > remote host is down, connection fails, etc.) The remedy in each case is > to catch the exception, log the error, and try the operation again > later. But there's no guaranteed-to-be-complete list in the Python docs > of all the exceptions that can be thrown. A new and surprising mode of > network failure can lead to an unhandled exception, unless you catch > everything. I would expect that catching socket.error (or even IOError) should catch all of those. "exception socket.error A subclass of IOError, this exception is raised for socket-related errors. It is recommended that you inspect its errno attribute to discriminate between different kinds of errors." > It's a retail application that would cause some business disruption and > a pissed off customer if the program went down. Also it's in an > embedded box on a customer site. It's not in Antarctica or anything > like that, but it's a few towns over, and someone would have to drive > there (probably through heavy traffic) if something went wrong that > power cycling the box couldn't fix. -- Terry Jan Reedy