Path: csiph.com!optima2.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!1.eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed8.news.xs4all.nl!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <python-python-list@m.gmane.org>
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; 'else:': 0.03; 'finally:': 0.05; 'badly': 0.07; 'creighton': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'wrote:': 0.16; 'first.': 0.18; 'laura': 0.18; 'try:': 0.18; '2015': 0.20; 'work,': 0.21; 'so.': 0.22; 'header:User-Agent:1': 0.26; 'header:X-Complaints-To:1': 0.26; 'fri,': 0.27; 'skip:d 20': 0.34; 'done': 0.35; 'false': 0.35; 'but': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'received:org': 0.37; 'missing': 0.37; 'wrong': 0.38; 'to:addr:python.org': 0.40; 'hope': 0.61; 'skip:n 10': 0.62; 'you.': 0.64; 'jul': 0.72; 'becker': 0.84; 'received:139': 0.91; 'try.': 0.91
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Neal Becker <ndbecker2@gmail.com>
Subject: Re: register cleanup handler
Date: Fri, 24 Jul 2015 12:01:58 -0400
References: <motjor$vv$1@ger.gmane.org> <201507241547.t6OFlh5t027843@fido.openend.se>
Mime-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7Bit
X-Gmane-NNTP-Posting-Host: exa2-in-fw-01-epn.hns.com
User-Agent: KNode/4.14.9
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.20+
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>
Newsgroups: comp.lang.python
Message-ID: <mailman.953.1437753734.3674.python-list@python.org>
Lines: 39
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1437753734 news.xs4all.nl 2906 [2001:888:2000:d::a6]:33839
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:94511

Laura Creighton wrote:

> In a message of Fri, 24 Jul 2015 10:57:30 -0400, Neal Becker writes:
>>I know we have try/finally, but I don't think that helps here, because
>>code_executed_unconditionally couldn't be inside the try.  Or am I missing
>>something obvious?
> 
> I think so.  Either that or I am badly misunderstanding you.  What is
> wrong with
> 
> try:
>    if (condition):
>       do_something_needing_cleanup
>    else:
>       do_something_else
>    code_executed_unconditionally
> finally:
>    do_cleanup
> 
> Laura

do_cleanup has do be done only if do_something_needing_cleanup was done 
first.

This would work, but is not very elegant.  I hope for a better way. 

need_cleanup = False
try:
   if (condition):
      do_something_needing_cleanup
      need_cleanup = True
   else:
      do_something_else
   code_executed_unconditionally
finally:
   if need_cleanup:
     do_cleanup