Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!newsfeed.xs4all.nl!newsfeed6.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 0.040 X-Spam-Evidence: '*H*': 0.92; '*S*': 0.00; '(at': 0.03; 'compiler': 0.07; 'exec': 0.07; 'prints': 0.07; 'globals': 0.09; 'namespace': 0.09; 'referenced': 0.09; 'namespace.': 0.16; 'parameter,': 0.16; 'program...': 0.16; 'help.': 0.19; 'variable': 0.21; 'sound': 0.22; "doesn't": 0.22; 'header:In-Reply-To:1': 0.22; 'restrict': 0.23; 'function': 0.26; 'skip:b 20': 0.26; "i'm": 0.27; 'sorry,': 0.29; 'module': 0.30; '"in': 0.30; 'version': 0.30; 'least': 0.31; 'print': 0.32; 'does': 0.32; 'to:addr:python-list': 0.34; 'header :User-Agent:1': 0.34; 'however,': 0.34; 'force': 0.34; "can't": 0.34; 'assignment': 0.35; 'function.': 0.35; 'visible': 0.35; 'installed': 0.35; 'thank': 0.35; 'but': 0.37; 'received:192': 0.38; 'subject:: ': 0.38; 'think': 0.38; 'got': 0.39; 'to:addr:python.org': 0.39; 'did': 0.40; 'your': 0.60; 'received:62': 0.67; 'works,': 0.68; 'discovered': 0.69; 'specialized': 0.71; '100': 0.72; 'locals': 0.84; 'received:192.168.0.100': 0.84; 'received:192.168.13': 0.84; 'received:62.179': 0.84; 'received:62.179.121': 0.84; 'received:upcmail.net': 0.84; '-->': 0.91 X-SourceIP: 89.132.76.204 Date: Sun, 31 Jul 2011 00:18:51 +0200 From: Laszlo Nagy User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110617 Thunderbird/3.1.11 MIME-Version: 1.0 To: python-list@python.org Subject: Re: eval, exec and execfile dilemma References: <4E346028.5000302@shopzeus.com> <4E34761C.7030609@stoneleaf.us> In-Reply-To: <4E34761C.7030609@stoneleaf.us> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Cloudmark-Analysis: v=1.1 cv=zlRBWuFCZaNL9+WHNm1pWLowY5Lx061w2zJBJiDkNAU= c=1 sm=0 a=869cbtyjxWwA:10 a=y3nyYLdweaIA:10 a=RSPf8KcgRHcA:10 a=8nJEP1OIZ-IA:10 a=ui-CF7pVqbpt-yn7fLQA:9 a=wPNLvfGTeEIA:10 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 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: 38 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1312064338 news.xs4all.nl 23863 [2001:888:2000:d::a6]:44184 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:10602 >> UnboundLocalError: local variable 'bar' referenced before assignment > > This works, though (at least it does on 2.7): > > --> exec "def foo():\n\tglobal bar\n\tbar+=1\n\treturn 1\n" > --> bar = 9 > --> foo() > 1 > --> bar > 10 > > Laszlo, why do you think you can't use exec? I'm sorry, first I was not aware of the "in globals locals" part. Then I also got an UnboundLocalError. Then I also figured out that I can use "global bar", but I did not want to. Reason: 100 functions/second installed to global namespace doesn't sound well. However, now I discovered the locals parameter, and I figured out that I can force the compiler to treat the name of the function to be a local name. I do this by reserving its name in locals. Then the compiler has no choice but to place it in the local namespace: locals = {'_f_':None} globals ={} # More specialized version in my program... exec "def _f_(a):\n\treturn a+1\n\n" in globals,locals print locals['_f_'](4) # prints '5' This is good because it is not interfering with module level globals(), nor the local namespace. Also good because I can restrict what is visible from inside the function. Thank you for your help. Best, Laszlo