Path: csiph.com!usenet.pasdenom.info!gegeweb.org!usenet-fr.net!nerim.net!novso.com!newsfeed.xs4all.nl!newsfeed1.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path: <rosuav@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.003
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'attribute': 0.07; 'think,': 0.07; '*args,': 0.09; 'calls.': 0.09; 'function,': 0.09; 'lookup': 0.09; 'methods,': 0.09; 'python': 0.11; 'def': 0.12; '(other': 0.16; '__init__,': 0.16; 'attributes,': 0.16; 'bugs.': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'itself,': 0.16; 'kwargs': 0.16; 'lambda': 0.16; 'subclass': 0.16; 'subject:object': 0.16; 'wrote:': 0.18; 'wed,': 0.18; 'example': 0.22; "aren't": 0.24; "haven't": 0.24; 'sort': 0.25; 'header:In- Reply-To:1': 0.27; 'point': 0.28; 'function': 0.29; 'chris': 0.29; 'am,': 0.29; 'restrict': 0.30; 'message-id:@mail.gmail.com': 0.30; 'getting': 0.31; '25,': 0.31; 'safely': 0.31; 'class': 0.32; 'not.': 0.33; 'skip:_ 10': 0.34; 'subject:the': 0.34; 'problem': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'there': 0.35; 'crazy': 0.36; 'method': 0.36; 'possible': 0.36; 'should': 0.36; 'work?': 0.38; 'whatever': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'that,': 0.38; 'to:addr:python.org': 0.39; 'called': 0.40; 'even': 0.60; 'ian': 0.60; "you're": 0.61; 'happen': 0.63; 'pick': 0.64; 'between': 0.67; '26,': 0.68; 'yourself': 0.78; 'safe.': 0.84; '2013': 0.98
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=arx5DISJaUgMVNPO/jHkis1Oc8uOz8aq71l9mXDZtSk=; b=Rz8FrPyJaar2pK899xqdsO//eqLkYs4uO/dLXTp/tUpUln1q4EUsjjLC7AMxb9W4l8 ChF3OaM+Bl4nkykxihLWGbUmMsdL+JDQHk06PUSt0A+3LWXxT4ro8kl2mQJc5NDpFoym pTnJuL4ZhStY+vO1iAp1hcthbwOdZx+pyo1dEpAFP8W1os8pyCouPMtGSdYTHrU8z6um Nh95hApEMlco5szLtEaKhhUtmBKclY5x1b67u65K6MvaxB05LCqaBZwMFzxIexJ+BrB9 aSw/RAzk4kWoFQFCICndBLG1NQCbkZb8tn7SOyAIbVEPKZ/jLAJNltHB6ttLi6ft0dXy 6I4Q==
MIME-Version: 1.0
X-Received: by 10.59.9.69 with SMTP id dq5mr597758ved.87.1372199988107; Tue, 25 Jun 2013 15:39:48 -0700 (PDT)
In-Reply-To: <CALwzid=VaCK10uUqTqjNfEU4BL3B9f1xvCEpsNTHu44Du+EQNQ@mail.gmail.com>
References: <15ba0011-bbf1-42f7-b3ea-1c1d4b70e56b@googlegroups.com> <51c66962$0$29999$c3e8da3$5496439d@news.astraweb.com> <20130623133546.GA2308@capricorn> <mailman.3729.1372004188.3114.python-list@python.org> <51c723b4$0$29999$c3e8da3$5496439d@news.astraweb.com> <51C74D6E.6030200@rece.vub.ac.be> <CALwzidnf0h3GUdeQFjwwhMYXXJVyOCFuE-kc564k-j_1icoC_g@mail.gmail.com> <CAPTjJmoeMX5FL=dQzW+W0D1W2BqSP=n+Z412Y_q5zS0gS7+0xg@mail.gmail.com> <CALwzid=VaCK10uUqTqjNfEU4BL3B9f1xvCEpsNTHu44Du+EQNQ@mail.gmail.com>
Date: Wed, 26 Jun 2013 08:39:47 +1000
Subject: Re: What is the semantics meaning of 'object'?
From: Chris Angelico <rosuav@gmail.com>
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 <python-list.python.org>
List-Unsubscribe: <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.3857.1372199996.3114.python-list@python.org>
Lines: 31
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1372199996 news.xs4all.nl 15996 [2001:888:2000:d::a6]:41402
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:49203

On Wed, Jun 26, 2013 at 8:25 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Tue, Jun 25, 2013 at 4:17 PM, Chris Angelico <rosuav@gmail.com> wrote:
>> The main problem is getting to the top/end of the call chain. Classic
>> example is with __init__, but the same problem can also happen with
>> other calls. Just a crazy theory, but would it be possible to
>> construct a black-holing object that, for any given method name,
>> returns a dummy function that ignores its args? (Other forms of
>> attribute lookup aren't going to be a problem, I think, so this can be
>> just methods/functions.) Then you just subclass from that all the
>> time, instead of from object itself, and you should be able to safely
>> call super's methods with whatever kwargs you haven't yourself
>> processed. Would that work?
>
> class BlackHole(object):
>     def __getattr__(self, attr):
>         return lambda *args, **kwargs: None
>
> There's no way to restrict it to just methods, because there's no
> fundamental difference in Python between methods and other attributes,
> and at the point that you're looking it up you have no way of knowing
> whether the result is about to be called or not.

Right, but what I mean is that you don't need any sort of
special-casing to pick an object type to return. Just return a
function, because that's going to be safe.

> And even if there were, this would be an excellent way to hide bugs.

Ehh, true. Don't know a way around that one. Meh.

ChrisA