Path: csiph.com!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!newsfeed.eweka.nl!eweka.nl!feeder3.eweka.nl!newsfeed.xs4all.nl!newsfeed5.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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'argument': 0.04; 'explicitly': 0.04; 'jeff': 0.04; 'attribute': 0.05; '*args,': 0.07; 'arguments': 0.07; 'python': 0.09; '**kwargs)': 0.09; '**kwargs):': 0.09; 'command.': 0.09; 'declarations': 0.09; 'default)': 0.09; 'preferable': 0.09; 'subject:using': 0.09; 'def': 0.10; 'oct': 0.16; 'wrote:': 0.17; '(or': 0.18; 'header:In- Reply-To:1': 0.25; 'am,': 0.27; 'message-id:@mail.gmail.com': 0.27; 'skip:_ 10': 0.29; 'probably': 0.29; 'class': 0.29; 'e.g.': 0.30; 'fri,': 0.30; 'keyword': 0.30; 'subject: ?': 0.30; 'skip:_ 30': 0.32; 'to:addr:python-list': 0.33; 'recommended': 0.33; 'received:google.com': 0.34; 'list': 0.35; 'skip:k 20': 0.35; 'so,': 0.35; 'doing': 0.35; 'received:209.85': 0.35; 'something': 0.35; 'there': 0.35; 'really': 0.36; 'skip:m 40': 0.36; 'method': 0.36; 'should': 0.36; 'possible': 0.37; 'signature': 0.37; 'received:209': 0.37; 'subject:: ': 0.38; 'instead': 0.39; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; '26,': 0.65; 'to:name:python': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=ExeNbS7+ulF8PUaX1Qtq8ga7TJOYRqhg6R/fOT8fcVU=; b=ZR92LDZV6gnEzh7QL6KRjyx3XuEmXKpDLm7cLp9PSOoUv/MglpEaNHa8y1X49S0Rau NFifoL93msZpumnzRrN9rMqDm5RQph0EioSPDQ3MKpdai3uEJyHI5ZhRsz0A/AePn2SN l1JXCiAGYX4Wog9/C2kG5vk97XXNADtWg3QbWzy5nHdNV4vH+3oe+CIxrQ1oKINXi1Xt sSDXaWcoGrbk3NQokHbVaG76MdcuKTVCWb5a5aIq+w7T5NUeJzIjd5bEOXPW4TBRQPtj lf4ASpej7XSrh7e1lIo9BK22onNZe/YYpqcdI8xzpPF498h5mPgFfH505FPMhk+v7HTu y2Zw== MIME-Version: 1.0 In-Reply-To: References: From: Ian Kelly Date: Fri, 26 Oct 2012 11:13:05 -0600 Subject: Re: Recommended way to unpack keyword arguments using **kwargs ? To: Python 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: 27 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1351271618 news.xs4all.nl 6909 [2001:888:2000:d::a6]:49182 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:32228 On Fri, Oct 26, 2012 at 10:58 AM, Jeff Jeffries wrote: > I have been doing the following to keep my class declarations short: > > class MyClass(MyOtherClass): > def __init__(self,*args,**kwargs): > self.MyAttr = kwargs.get('Attribute',None) #To get a default > MyOtherClass.__init__(self,*args,**kwargs) > > Is there a recommended way to get keyword arguments (or default) when using > ** notation? It's better form to use .pop() instead of .get(), as if MyClass is receiving the argument then MyOtherClass is probably not expecting it. If using Python 3, you can use the keyword-only argument syntax: def __init__(self, *args, attribute=None, **kwargs): # Do something with attribute MyOtherClass.__init__(self, *args, **kwargs) Either way, you should really only do this when there are a large number of possible arguments or you don't really know what arguments to expect. When practical to do so, it is preferable to explicitly list the arguments so that the method signature can be inspected, e.g. by the help() command.