Path: csiph.com!usenet.pasdenom.info!goblin2!goblin.stu.neva.ru!newsfeed.xs4all.nl!newsfeed2.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; 'example:': 0.03; 'from:addr:yahoo.co.uk': 0.04; 'modified:': 0.05; 'context': 0.07; 'finally:': 0.07; 'practice,': 0.07; 'result,': 0.07; 'subject:file': 0.07; 'suppose': 0.07; 'string': 0.09; 'lawrence': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'thrown': 0.09; 'tismer': 0.09; 'try:': 0.09; 'python': 0.11; "'rb')": 0.16; '(everything': 0.16; 'code?': 0.16; 'ioerror': 0.16; 'ioerror:': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'subject:possible': 0.16; 'unix,': 0.16; 'exception': 0.16; 'language': 0.16; 'wrote:': 0.18; 'work,': 0.20; '>>>': 0.22; 'programming': 0.22; 'header:User-Agent:1': 0.23; 'guys': 0.24; 'cheers,': 0.24; 'file.': 0.24; 'handling': 0.26; 'second': 0.26; 'pass': 0.26; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply- To:1': 0.27; '???': 0.30; "i'm": 0.30; 'lines': 0.31; 'way?': 0.31; 'another': 0.32; 'open': 0.33; "can't": 0.35; 'except': 0.35; 'something': 0.35; 'but': 0.35; 'there': 0.35; 'data,': 0.36; 'impression': 0.36; 'possible': 0.36; 'subject:?': 0.36; 'hi,': 0.36; 'should': 0.36; 'christian': 0.38; 'manager': 0.38; 'nov': 0.38; 'to:addr:python-list': 0.38; 'bad': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.39; 'enough': 0.39; 'either': 0.39; 'received:org': 0.40; 'how': 0.40; 'break': 0.61; 'world.': 0.61; 'more': 0.64; 'needing': 0.65; 'beats': 0.84; 'received:2': 0.84; 'subject:Using': 0.84; 'subject:handle': 0.84; 'subject:try': 0.84; 'victor': 0.84; '2013': 0.98 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Mark Lawrence Subject: Re: Using try-catch to handle multiple possible file types? Date: Wed, 20 Nov 2013 01:50:02 +0000 References: <8379f7c2-c248-4a67-82ed-2d288a1635d2@googlegroups.com> <4c5f2389-177c-4056-8857-19e2950f8aa7@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: host-2-98-196-198.as13285.net User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 In-Reply-To: <4c5f2389-177c-4056-8857-19e2950f8aa7@googlegroups.com> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 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: 91 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1384913119 news.xs4all.nl 15923 [2001:888:2000:d::a6]:42394 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:60047 On 20/11/2013 00:30, Victor Hooi wrote: > Hi, > > Is either approach (try-excepts, or using libmagic) considered more idiomatic? What would you guys prefer yourselves? > > Also, is it possible to use either approach with a context manager ("with"), without duplicating lots of code? > > For example: > > try: > with gzip.open('blah.txt', 'rb') as f: > for line in f: > print(line) > except IOError as e: > with open('blah.txt', 'rb') as f: > for line in f: > print(line) > > I'm not sure of how to do this without needing to duplicating the processing lines (everything inside the with)? > > And using: > > try: > f = gzip.open('blah.txt', 'rb') > except IOError as e: > f = open('blah.txt', 'rb') > finally: > for line in f: > print(line) > > won't work, since the exception won't get thrown until you actually try to open the file. Plus, I'm under the impression that I should be using context-managers where I can. > > Also, on another note, python-magic will return a string as a result, e.g.: > > gzip compressed data, was "blah.txt", from Unix, last modified: Wed Nov 20 10:48:35 2013 > > I suppose it's enough to just do a? > > if "gzip compressed data" in results: > > or is there a better way? > > Cheers, > Victor > > On Tuesday, 19 November 2013 20:36:47 UTC+11, Mark Lawrence wrote: >> On 19/11/2013 07:13, Victor Hooi wrote: >> >>> >> >>> So basically, using exception handling for flow-control. >> >>> >> >>> However, is that considered bad practice, or un-Pythonic? >> >>> >> >> >> >> If it works for you use it, practicality beats purity :) >> >> >> >> -- >> >> Python is the second best programming language in the world. >> >> But the best has yet to be invented. Christian Tismer >> >> >> >> Mark Lawrence Something like for filetype in filetypes: try: process(filetype) break except IOError: pass ??? as it's 01:50 GMT and I can't sleep :( -- Python is the second best programming language in the world. But the best has yet to be invented. Christian Tismer Mark Lawrence