Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!news.mixmin.net!news2.arglkargh.de!news.wiretrip.org!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path: <t@jollybox.de>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.010
X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'else:': 0.03; 'terry': 0.07; 'caller': 0.09; 'line:': 0.09; 'am,': 0.13; 'subject:file': 0.13; 'wrote:': 0.15; "'rb')": 0.16; 'billy': 0.16; 'received:192.168.1.40': 0.16; 'pm,': 0.16; '>>>': 0.16; 'def': 0.16; 'any,': 0.19; 'header:In-Reply-To:1': 0.22; 'trying': 0.23; 'function': 0.26; "i'm": 0.27; 'raise': 0.28; 'yield': 0.29; 'problem': 0.29; 'confused': 0.30; 'tail': 0.30; 'lines': 0.31; 'actually': 0.33; 'to:addr:python-list': 0.34; 'header:User- Agent:1': 0.34; 'there': 0.34; 'then.': 0.35; '(not': 0.35; 'subject:How': 0.36; 'skip:o 20': 0.36; 'file': 0.36; 'but': 0.37; 'received:192': 0.38; 'subject:: ': 0.38; 'received:192.168.1': 0.39; 'data': 0.39; 'to:addr:python.org': 0.39; 'read,': 0.40; 'called': 0.40; 'bill': 0.40; 'received:62': 0.67; '04:46': 0.84; 'avoid.': 0.84; 'from:addr:t': 0.84; 'subject:write': 0.84
Date: Tue, 12 Jul 2011 21:05:52 +0200
From: Thomas Jollans <t@jollybox.de>
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110626 Iceowl/1.0b2 Icedove/3.1.11
MIME-Version: 1.0
To: python-list@python.org
Subject: Re: How to write a file generator
References: <ivhmoc$6t3$1@speranza.aioe.org>	<mailman.944.1310485982.1164.python-list@python.org> <ivhthn$peg$1@speranza.aioe.org>
In-Reply-To: <ivhthn$peg$1@speranza.aioe.org>
X-Enigmail-Version: 1.1.2
OpenPGP: id=5C8691ED
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <http://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: <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.952.1310497555.1164.python-list@python.org>
Lines: 34
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1310497555 news.xs4all.nl 23861 [2001:888:2000:d::a6]:37083
X-Complaints-To: abuse@xs4all.nl
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:9342

On 07/12/2011 06:42 PM, Billy Mays wrote:
> On 07/12/2011 11:52 AM, Thomas Jollans wrote:
>> On 07/12/2011 04:46 PM, Billy Mays wrote:
>>> I want to make a generator that will return lines from the tail of
>>> /var/log/syslog if there are any, but my function is reopening the file
>>> each call:
>>>
>>> def getLines():
>>>      with open('/var/log/syslog', 'rb') as f:
>>>          while True:
>>>              line = f.readline()
>>>              if line:
>>>                  yield line
>>>              else:
>>>                  raise StopIteration
>>>
>>>
>>> I know the problem lies with the StopIteration, but I'm not sure how to
>>> tell the caller that there are no more lines for now.
>>>
>>> -- 
>>> Bill
>>
>> http://stackoverflow.com/questions/1475950/tail-f-in-python-with-no-time-sleep
>>
> 
> 
> That was actually the behavior I was trying to avoid.  If there is no
> data to be read, the call will hang.  That function is actually called
> by a webserver (from wsgiref) so it cannot hang indefinitely.


What Terry said, then. (Not Bruno, I confused that. Sorry for sending a
mail both short and wrong.)