Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Matt Wheeler Newsgroups: comp.lang.python Subject: Re: modifying a standard module? (was: Re: tarfile : read from a socket?) Date: Fri, 12 Feb 2016 20:53:16 +0000 Lines: 63 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: news.uni-berlin.de GAOvkrHQhXHklDkz7Xu/uQiq2bQiOg5TarPwPvn/8jNw== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; '+++': 0.03; 'modified': 0.05; '*args,': 0.07; 'false,': 0.07; 'cc:addr:python-list': 0.09; '"%s"\'': 0.09; 'imports': 0.09; 'messing': 0.09; 'path)': 0.09; 'subclass': 0.09; 'subject:module': 0.09; 'python': 0.10; ':-)': 0.12; 'output': 0.13; 'def': 0.13; 'suggest': 0.15; 'argument': 0.15; '2016': 0.16; 'enough:': 0.16; 'function?': 0.16; 'hack,': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; 'subject:?)': 0.16; 'substitute': 0.16; 'tarfile': 0.16; 'wrote:': 0.16; 'library': 0.20; 'cc:2**0': 0.20; 'cc:addr:python.org': 0.20; '+0200': 0.20; 'cc:no real name:2**0': 0.22; 'import': 0.24; 'patch': 0.24; 'header:In-Reply-To:1': 0.24; 'sort': 0.25; 'module': 0.25; 'distribute': 0.27; 'message-id:@mail.gmail.com': 0.27; '+0100': 0.27; 'function': 0.28; '---': 0.28; '**kwargs)': 0.29; '**kwargs):': 0.29; 'question:': 0.29; 'tar': 0.29; 'print': 0.30; 'subject: : ': 0.30; 'anyone': 0.32; "can't": 0.32; 'class': 0.33; 'extract': 0.33; 'skip:d 20': 0.34; 'gives': 0.35; 'received:google.com': 0.35; 'next': 0.35; 'skip:. 20': 0.35; 'received:74.125.82': 0.35; 'step': 0.36; 'but': 0.36; 'there': 0.36; 'subject:: ': 0.37; 'really': 0.37; 'subject:from': 0.39; 'your': 0.60; 'default': 0.61; 'skip:n 10': 0.62; 'within': 0.64; 'reverse': 0.66; 'member,': 0.67; 'risk': 0.68; "else's": 0.84; 'from:addr:m': 0.84; 'received:74.125.82.41': 0.84; 'subject:read': 0.84 X-Virus-Scanned: Debian amavisd-new at membrane.funkyhat.net X-Gm-Message-State: AG10YORVWWxnXYFLMhvIDBtN/Nb1CSaNN0gimK3aRYfqo+nKYghLH0rcK7o/uPyyd3/jmIcJrv7zoz0euCl/4w== X-Received: by 10.194.184.171 with SMTP id ev11mr3675472wjc.44.1455310416580; Fri, 12 Feb 2016 12:53:36 -0800 (PST) In-Reply-To: X-Gmail-Original-Message-ID: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.21rc2 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Xref: csiph.com comp.lang.python:102871 On 11 February 2016 at 17:10, Ulli Horlacher wrote: > > Ulli Horlacher wrote: > As a hack, I modified the standard library module tarfile.py: > > root@diaspora:/usr/lib/python2.7# vv -d > --- ./.versions/tarfile.py~1~ 2015-06-22 21:59:27.000000000 +0200 > +++ tarfile.py 2016-02-11 18:01:50.185555952 +0100 > @@ -2045,6 +2045,7 @@ > directories.append(tarinfo) > tarinfo = copy.copy(tarinfo) > tarinfo.mode = 0700 > + print('untar "%s"' % tarinfo.name) > self.extract(tarinfo, path) > > # Reverse sort directories. > > > This gives me exact the output I want :-) > > BUT I want to distribute my program and all others will not see the tar > extracting information. > > Now my question: > > How can I substitute the standard module function tarfile.extractall() with > my own function? import tarfile def new_extractall(self, *args, **kwargs): print("I am a function. Woohoo!") tarfile.TarFile.extractall = new_extractall But bear in mind that that will change tarfile.extractall for every single module that imports it within the same python process. Is that really what you want? Is there a reason you can't subclass TarFile as others have suggested? Perhaps even this is enough: class NoisyTarFile(TarFile): """untested, sorry""" def extract(self, member, *args, **kwargs): print('extracting "%s"' % member.name) super(NoisyTarFile, self).extract(member, *args, **kwargs) As the very next step after your print in extractall is a call to extract anyway? If you must patch the standard library tarfile module then I would suggest patching it to have an extra, default False, argument to enable your printing behaviour, so you don't risk messing up anyone else's use of it. -- Matt Wheeler http://funkyh.at