Path: csiph.com!eeepc.pasdenom.info!news.pasdenom.info!news.dougwise.org!gegeweb.org!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!feeder.news-service.com!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; 'defines': 0.05; 'interpreter': 0.05; 'args': 0.07; 'arguments.': 0.09; 'function:': 0.09; 'positional': 0.09; 'tuple': 0.09; '>>>': 0.11; 'am,': 0.13; 'wrote:': 0.14; 'def': 0.14; 'argument': 0.15; 'arguments': 0.15; 'traceback': 0.15; '(1,': 0.16; '(normally': 0.16; '**kwargs)': 0.16; '*args):': 0.16; 'arguments:': 0.16; 'class)': 0.16; 'function;': 0.16; 'precede': 0.16; 'subject:def': 0.16; 'cc:no real name:2**0': 0.17; '(most': 0.17; 'cheers,': 0.17; 'cc:2**0': 0.21; 'object': 0.22; 'jan': 0.22; 'last):': 0.23; 'header:In-Reply-To:1': 0.23; 'cc:addr:python-list': 0.24; 'parameters': 0.25; 'named': 0.26; 'function': 0.27; 'url:blog': 0.27; 'instead': 0.28; 'functions,': 0.28; 'least': 0.29; 'message-id:@mail.gmail.com': 0.29; "(i'm": 0.30; 'basically,': 0.30; 'grasp': 0.30; 'sun,': 0.30; 'typeerror:': 0.30; 'except': 0.30; 'cc:addr:python.org': 0.30; 'no.': 0.33; 'does': 0.33; 'file': 0.34; '"",': 0.34; 'hi,': 0.34; 'print': 0.35; 'url:docs': 0.35; 'but': 0.36; 'keyword': 0.36; 'used': 0.36; 'received:209.85': 0.38; 'next': 0.38; 'received:google.com': 0.38; 'i.e.': 0.38; 'url:org': 0.38; 'subject:: ': 0.39; 'url:python': 0.39; 'your': 0.61; 'receive': 0.68; 'concept': 0.70; '30,': 0.72; '11:26': 0.84; 'complexities': 0.84; 'friend!': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rebertia.com; s=google; h=domainkey-signature:mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=7+AxkTzFSpPG3PslcOGVC+abUaJAa3g93ttbls26FpI=; b=UN803NF9s98YtNeEWzcqU3sd05MR6H3+crw3JIPCabtQimvu3F0S1DL9cvANYFqRTX tMZ1QHuWEMbA9+qSs/ZsMkZI1m7cv6w7TPphWXsbYH50mRcv2QuwoGbdRcHJxNx8WUXz BWn+EB70XiOrKGT0pjf1zO5aDmXHo9JdQpuuA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=rebertia.com; s=google; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=OUeOCVd5rNWevXOQsXIK2Z7i3g3xNxs0gHSDSoivG/joY/UjcmpEMcKEBZV2q9JRwX 1xVUafkPWZzfe3b/4DKW74ZyUzMRr5gEZggKlfE6nCx+qAQezHss2QTl2sMLTaMIt4MC ogQ9ZtLvko99RFivSZIrb1tngRNEgecAIi3R0= MIME-Version: 1.0 Sender: chris@rebertia.com In-Reply-To: <17945aea-21b6-45b5-9c09-e602143f755e@k4g2000pre.googlegroups.com> References: <17945aea-21b6-45b5-9c09-e602143f755e@k4g2000pre.googlegroups.com> Date: Sun, 30 Jan 2011 11:54:38 -0800 X-Google-Sender-Auth: ivNcDgLpKCR2YqoPRR30_kHJ-xE Subject: Re: Understanding def foo(*args) From: Chris Rebert To: sl33k_ Content-Type: text/plain; charset=UTF-8 Cc: python-list@python.org 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: 65 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1296417281 news.xs4all.nl 81475 [::ffff:82.94.164.166]:48143 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:55903 On Sun, Jan 30, 2011 at 11:26 AM, sl33k_ wrote: > Hi, > > I am struggling to grasp this concept about def foo(*args). The interactive interpreter is your friend! Try experimenting with it next time! http://docs.python.org/tutorial/controlflow.html#arbitrary-argument-lists That `def` defines a variadic function; i.e. a function which takes an arbitrary number of positional arguments. `args` will be a tuple of all the positional arguments passed to the function: >>> def foo(*args): ... print args ... >>> foo(1) (1,) >>> foo(1,2) (1, 2) >>> foo(1,2,3) (1, 2, 3) If positional parameters precede the *-parameter, then they are required and the *-parameter will receive any additional arguments: >>> def qux(a, b, *args): ... print 'a is', a ... print 'b is', b ... print 'args is', args ... >>> qux(1) Traceback (most recent call last): File "", line 1, in TypeError: qux() takes at least 2 arguments (1 given) >>> qux(1, 2) a is 1 b is 2 args is () >>> qux(1, 2, 3) a is 1 b is 2 args is (3,) >>> qux(1, 2, 3, 4) a is 1 b is 2 args is (3, 4) > Also, what is def bar(*args, *kwargs)? You meant: def bar(*args, **kwargs) See http://docs.python.org/tutorial/controlflow.html#keyword-arguments Basically, the **-parameter is like the *-parameter, except for keyword arguments instead of positional arguments. > Also, can the terms method and function be used interchangeably? No. A method is function that is associated with an object (normally via a class) and takes this object as its first argument (typically named "self"). A function does not have any of these requirements. Thus, all method are functions, but the reverse is not true. (I'm ignoring complexities like classmethods and staticmethods for simplicity.) Cheers, Chris -- http://blog.rebertia.com