Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed1a.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': 0.05; 'assign': 0.07; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:instance': 0.09; 'variable,': 0.09; 'python': 0.11; 'language,': 0.12; '__init__,': 0.16; '__lt__': 0.16; 'argument.': 0.16; 'crude': 0.16; 'itself,': 0.16; 'ought': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'set,': 0.16; 'subject: \n ': 0.16; 'subject:class': 0.16; 'subject:variable': 0.16; 'language': 0.16; 'wrote:': 0.18; 'wed,': 0.18; 'meant': 0.20; '(the': 0.22; 'aug': 0.22; 'header :User-Agent:1': 0.23; 'received:comcast.net': 0.24; 'defined': 0.27; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'function': 0.29; 'chris': 0.29; 'am,': 0.29; '13,': 0.31; 'names.': 0.31; 'class': 0.32; 'becomes': 0.33; 'subject:from': 0.34; 'subject: (': 0.35; 'something': 0.35; 'definition': 0.35; 'but': 0.35; 'really': 0.36; 'like,': 0.36; 'method': 0.36; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'first': 0.61; 'name': 0.63; 'significance': 0.84; 'on?': 0.91 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Ned Batchelder Subject: Re: Arbitrary dunder attributes (was Re: odd difference calling function from class or instance variable) Date: Wed, 13 Aug 2014 08:11:05 -0400 References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: c-50-133-228-126.hsd1.ma.comcast.net User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 In-Reply-To: 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: 33 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1407931879 news.xs4all.nl 2899 [2001:888:2000:d::a6]:37586 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:76190 On 8/13/14 5:51 AM, Chris Angelico wrote: > On Wed, Aug 13, 2014 at 7:06 PM, GregS wrote: >> When I assign the reference as a class variable, the reference has __self__ >> set, too, so I get an extra argument passed to the function. If I assign >> the reference as an instance variable, then __self__ is unset so no extra >> argument. > > Spin-off from Greg's thread. > > The bound method object stores a reference to the original object (the > thing that becomes the first argument to the target function) in > __self__ (and the function in __func__). ISTM this ought to be _self > (and _func), as it's intended to be private; is it really something > that has language-level significance on par with __lt__ and so on? > > ChrisA > As I see it, dunder names are those whose meaning is defined by the Python language (and/or implementation?), and whose use is typically behind-the-scenes. So "len" is defined by the language, but is meant to be front-and-center, so it has a nice name. __init__, __lt__, and __self__, have meanings and uses defined by Python itself, and so are reasonable as dunder names. This is a crude namespacing: Python can use any name it likes so long as its a dunder name, and I can use any name I like, so long as it isn't. Yes, the definition is fuzzy.... :) -- Ned Batchelder, http://nedbatchelder.com