Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!selfless.tophat.at!feeder.erje.net!newsfeed.xs4all.nl!newsfeed5.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; 'subject:module': 0.04; 'passes': 0.05; 'string,': 0.05; 'written.': 0.07; 'python': 0.07; ':-)': 0.07; 'from:addr:python': 0.09; 'pm,': 0.11; 'this:': 0.11; 'exception': 0.12; 'def': 0.13; 'wrote:': 0.14; '42,': 0.16; 'clause,': 0.16; 'docs.': 0.16; 'from:addr:mrabarnett.plus.com': 0.16; 'from:name:mrab': 0.16; 'keyerror:': 0.16; 'message- id:@mrabarnett.plus.com': 0.16; 'received:84.92': 0.16; 'received:84.92.122': 0.16; 'received:84.92.122.60': 0.16; 'received:84.93': 0.16; 'received:84.93.230': 0.16; 'reply-to:addr :python-list': 0.16; 'roy': 0.16; 'invalid': 0.16; 'code': 0.22; 'header:In-Reply-To:1': 0.22; 'somebody': 0.25; 'received:84': 0.25; 'function': 0.27; 'raise': 0.29; "can't": 0.31; 'to:addr :python-list': 0.32; 'got': 0.34; 'there': 0.35; 'header:User- Agent:1': 0.35; 'like:': 0.35; 'reply-to:addr:python.org': 0.35; 'trigger': 0.35; 'try:': 0.35; 'doing': 0.36; 'setting': 0.36; 'andrew': 0.38; 'so,': 0.38; 'help': 0.39; 'to:addr:python.org': 0.39; 'except': 0.39; 'reply-to:no real name:2**0': 0.72; 'header :Reply-To:1': 0.72; 'job?': 0.84; 'subject:handle': 0.84 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AlEHALAzzE1UXebj/2dsb2JhbACYAY14d8k9hhUElCOKQg Date: Thu, 12 May 2011 20:25:21 +0100 From: MRAB User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10 MIME-Version: 1.0 To: python-list@python.org Subject: Re: Proper way to handle errors in a module References: <4DCC318E.7020809@gmail.com> In-Reply-To: <4DCC318E.7020809@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list Reply-To: python-list@python.org 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: 27 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1305228330 news.xs4all.nl 41114 [::ffff:82.94.164.166]:41222 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:5251 On 12/05/2011 20:14, Andrew Berg wrote: > On 2011.05.11 01:05 PM, Roy Smith wrote: >> You want to raise specific errors. Let's say you've got a function like >> this: >> >> def airspeed(swallow): >> speeds = {"european": 42, >> "african", 196} >> return speeds[swallow] >> >> If somebody passes an invalid string, it will raise KeyError as written. >> Better to do something like: >> >> def airspeed(swallow): >> speeds = {"european": 42, >> "african", 196} >> try: >> return speeds[swallow] >> except KeyError: >> raise UnknownBirdError(swallow) > Is there any way to do this without purposely setting up the code to > trigger an arbitrary exception if the function can't do its job? That > is, can I raise an UnknownBirdError outside of an except clause, and if > so, how? I can't find much help for doing this in Python 3, even in the > official docs. > You can raise an exception wherever you like! :-)