Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed4a.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path: <python-python-list@m.gmane.org>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.004
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'float': 0.07; 'builtin': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'jan': 0.12; '(about': 0.16; 'bool': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'subclass': 0.16; 'wrote:': 0.18; '>>>': 0.22; 'header:User-Agent:1': 0.23; 'pass': 0.26; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'andrew': 0.30; 'class': 0.32; 'not.': 0.33; 'classes': 0.35; 'there': 0.35; 'ahead': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'to:addr:python.org': 0.39; 'received:org': 0.40; '5.6': 0.84; 'received:fios.verizon.net': 0.84; 'received:108': 0.93
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Comparisons and sorting of a numeric class....
Date: Tue, 06 Jan 2015 21:34:57 -0500
References: <54ABB88A.7070504@r3dsolutions.com> <54ABC52A.1050507@davea.name> <54ABE383.3020801@r3dsolutions.com> <54ABEAD9.8070000@davea.name> <54AC938C.7040206@r3dsolutions.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Gmane-NNTP-Posting-Host: pool-108-16-203-145.phlapa.fios.verizon.net
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0
In-Reply-To: <54AC938C.7040206@r3dsolutions.com>
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: <https://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: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.17427.1420598144.18130.python-list@python.org>
Lines: 18
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1420598144 news.xs4all.nl 2942 [2001:888:2000:d::a6]:38337
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:83277

On 1/6/2015 9:01 PM, Andrew Robinson wrote:

[snip]

There are very few (about 4) builtin classes that cannot be subclassed. 
  bool is one of those few, float is not.  Go ahead and subclass it.

 >>> class F(float): pass

 >>> F
<class '__main__.F'>
 >>> F(2.3) + F(3.3)
5.6


-- 
Terry Jan Reedy