Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Cameron Simpson <cs@zip.com.au>
Newsgroups: comp.lang.python
Subject: Re: Will file be closed automatically in a "for ... in open..." statement?
Date: Thu, 18 Feb 2016 13:22:49 +1100
Lines: 23
Message-ID: <mailman.229.1455762179.22075.python-list@python.org>
References: <na38t6$vi6$1@ger.gmane.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
X-Trace: news.uni-berlin.de 3HU9+ZO9QJtWOnHnTM8rKQ1wwjOszz61fSIa0nYlQ4Jg==
Return-Path: <cameron@cskk.homeip.net>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.005
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'subject:file': 0.07; 'subject:skip:a 10': 0.09; 'exception': 0.13; '"for"': 0.16; '>on': 0.16; 'better?': 0.16; 'from:addr:cs': 0.16; 'from:addr:zip.com.au': 0.16; 'from:name:cameron simpson': 0.16; 'message-id:@cskk.homeip.net': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; 'simpson': 0.16; 'subject:closed': 0.16; 'wrote:': 0.16; 'lawrence': 0.22; 'cheers,': 0.22; 'somewhere': 0.24; 'header:In-Reply-To:1': 0.24; 'header:User-Agent:1': 0.26; '(early': 0.29; 'etc).': 0.29; 'thread,': 0.29; "i'm": 0.30; 'certainly': 0.30; 'statement': 0.32; 'his/her': 0.33; 'open': 0.33; 'similar': 0.33; 'file': 0.34; 'handle': 0.34; 'skip:> 10': 0.35; 'but': 0.36; 'flow': 0.36; 'to:addr:python-list': 0.36; 'subject:?': 0.36; 'subject:: ': 0.37; 'charset:us-ascii': 0.37; 'received:localdomain': 0.38; 'sure': 0.39; 'enough': 0.39; 'to:addr:python.org': 0.40; 'mark': 0.40; 'some': 0.40; 'face': 0.64; 'cameron': 0.66
Content-Disposition: inline
In-Reply-To: <na38t6$vi6$1@ger.gmane.org>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.21rc2
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Xref: csiph.com comp.lang.python:103080

On 18Feb2016 02:05, Mark Lawrence <breamoreboy@yahoo.co.uk> wrote:
>On 18/02/2016 01:29, jfong@ms4.hinet.net wrote:
>>The "for ... open ..." is definitely not a good design pattern. It opens a file at "for" block but leaves it closed somewhere in the sky.
>>
>
>Hardly, as all ready explained, but how about this
>
>handle = open('foo.txt')
>for line in handle :
>    ...do something...
>handle.close()
>
>Is that better?

As already discussed in this thread, not in the face of an exception inside the 
loop or some other change of flow control (early "return" statement etc).

I'm pretty sure jfong understands the issues now, certainly enough to make 
his/her own decisions on the benefits and risks of with versus "for ... open" 
and similar variants.

Cheers,
Cameron Simpson <cs@zip.com.au>