Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder2.hal-mli.net!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 0.011 X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'debugging': 0.05; 'python': 0.09; '###': 0.09; 'received:mail-vb0-f46.google.com': 0.09; '(read': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'wrote:': 0.17; 'have:': 0.17; 'instance': 0.17; 'instance,': 0.17; 'variables': 0.17; '(in': 0.18; 'jan': 0.18; 'received:209.85.212.46': 0.18; 'question.': 0.20; 'written': 0.20; "i'd": 0.22; 'example': 0.23; '15,': 0.23; 'statement': 0.23; 'header:In-Reply-To:1': 0.25; '(which': 0.26; 'am,': 0.27; '(3)': 0.27; 'c++': 0.27; 'to?': 0.27; 'message- id:@mail.gmail.com': 0.27; 'lines': 0.28; 'received:209.85.212': 0.28; 'python).': 0.29; 'case,': 0.29; 'definition': 0.29; 'function': 0.30; '(2)': 0.32; 'to:addr:python-list': 0.33; 'received:google.com': 0.34; '(1)': 0.34; 'received:209.85': 0.35; 'tool': 0.36; 'subject: (': 0.36; 'received:209': 0.37; 'subject:: ': 0.38; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'your': 0.60; 'state.': 0.71; '2013': 0.84; 'etc,': 0.84; 'subject:read': 0.84; 'subject:write': 0.84; 'fibonacci': 0.91; 'write:': 0.91 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=/hFBaK9qCHZyKD3hkcDBfhpGCxQb2fe0bo3IKTDcAKE=; b=Hzb5PC3nmnUv7tTu31yCgKEIBFI545DLKLa116NlNxKH8bHnZdblIqC5uA2KZ9+hXm 83KJv2RoGwSufLKeYs/+p0Rd/Fg6yMsZp1jI0wx/DXP7SGwB0BauLP4OB/afETXBHv2R QWTXe7AWL/ktbAUSIa6hD8FYLi3BnKmSKqYhTxZt/J6r/VRqj2YUzdtopHTLVIbPUET+ okAs8L1WSmkVWyPLty8MohzP5YY1t1trAkGPeTdo7SZdOgsbqeW/nQfJPVxUUHAhAidf 4OGR5bFp0maE7tqD2tlGjMe9TfUxioBVSG45vSRDJ8GWKM21TyijifDBTvjCFPEpkL2N ymJg== MIME-Version: 1.0 In-Reply-To: <46c8a630-de27-41dc-8b8b-1951ba747447@googlegroups.com> References: <46c8a630-de27-41dc-8b8b-1951ba747447@googlegroups.com> Date: Tue, 15 Jan 2013 08:28:28 +1100 Subject: Re: Finding the variables (read or write) From: Chris Angelico To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 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: 24 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1358198911 news.xs4all.nl 6903 [2001:888:2000:d::a6]:49715 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:36821 On Tue, Jan 15, 2013 at 6:48 AM, wrote: > I'd like to develop a small debugging tool for python programs.In Dynamic Slicing How can I find the variables that are accessed in a statement? And find the type of access (read or write) for those variables (in Python). > ### Write: A statement can change the program state. > ### Read : A statement can read the program state . > **For example in these 4 lines we have: > (1) x = a+b => write{x} & read{a,b} > (2) y=6 => write{y} & read{} > (3) while(n>1) => write{} & read{n} > (4) n=n-1 => write{n} & read{n} An interesting question. What's your definition of "variable"? For instance, what is written and what is read by this statement: self.lst[2] += 4 Is "self.lst" considered a variable? (In C++ etc, this would be a member function manipulating an instance variable.) Or is "self" the variable? And in either case, was it written to? What about: self.lst.append(self.lst[-1]+self.lst[-2]) (which might collect Fibonacci numbers)? ChrisA