Re: dict: keys() and values() order guaranteed to be same?

Path	csiph.com!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed5.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 0.006
X-Spam-Evidence	'H': 0.99; 'S': 0.00; 'explicitly': 0.04; '(although': 0.09; 'dict': 0.09; 'received:mail- vb0-f46.google.com': 0.09; 'subject:keys': 0.09; 'subject:same': 0.09; "wouldn't": 0.11; '24,': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'subject:values': 0.16; 'tables,': 0.16; 'wrote:': 0.17; 'received:209.85.212.46': 0.18; "i'd": 0.22; 'header:In-Reply-To:1': 0.25; 'am,': 0.27; 'tree': 0.27; 'message-id:@mail.gmail.com': 0.27; 'received:209.85.212': 0.28; "d'aprano": 0.29; 'dictionary': 0.29; 'enforce': 0.29; 'hash': 0.29; 'steven': 0.29; 'that.': 0.30; 'implement': 0.32; 'could': 0.32; 'to:addr:python-list': 0.33; 'likely': 0.33; 'received:google.com': 0.34; 'subject:?': 0.35; 'received:209.85': 0.35; 'but': 0.36; 'does': 0.37; 'quite': 0.37; 'rather': 0.37; 'received:209': 0.37; 'subject:: ': 0.38; 'mean': 0.38; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'think': 0.40; 'skip:n 10': 0.63; 'jul': 0.65; 'promise': 0.65; "it'd": 0.84; 'tree,': 0.84
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=NqFO3xZsDr+rKYaR+/vtSh1dWzAySIyHA0ObMkzy7+c=; b=eFEBiH/i5EY6pQza3EcKQulqQdBL+20UTHx4RXUK9+kriiotX/C+8WdBO8pXgBdRlv BJyrYU6VtStT7WocnKnSZhYahTfgAxqUf/MqHPa+grItkkNXjBOTeSBwkfSSYZN1L8zM 1wl6SB26/M/FIs+VNSIMiLRTVIZZgcIpK7BJDDyG54aoGNv63+kEGsFFB9QbjXWi28pF FsdmLWdbjS9maITg9/NdnNPiYjS6QxWnh291kr7JVYzVD4aCYu1bH0L4MlGTAVYGP2cG 8H5ul13MAxce++8BVesk/6TMDG9BcStVchFXtvHO/5ZFxxM465aCdVpAeqxjR/IHOfng HZoQ==
MIME-Version	1.0
In-Reply-To	<500d6bb2$0$29978$c3e8da3$5496439d@news.astraweb.com>
References	<jujc6j$rk5$1@speranza.aioe.org> <500D383A.9090500@phihag.de> <mailman.2462.1343044733.4697.python-list@python.org> <500d6bb2$0$29978$c3e8da3$5496439d@news.astraweb.com>
Date	Tue, 24 Jul 2012 02:18:54 +1000
Subject	Re: dict: keys() and values() order guaranteed to be same?
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	2.1.12
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.2487.1343060336.4697.python-list@python.org> (permalink)
Lines	15
NNTP-Posting-Host	2001:888:2000:d::a6
X-Trace	1343060336 news.xs4all.nl 6891 [2001:888:2000:d::a6]:53876
X-Complaints-To	abuse@xs4all.nl
Xref	csiph.com comp.lang.python:25899

Show key headers only | View raw

On Tue, Jul 24, 2012 at 1:20 AM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> (Although if you think about the implementation of dicts as hash tables,
> it does seem likely that it is trivial to enforce this -- one would have
> to work *harder* to break that promise than to keep it.)

However, it would be quite reasonable to implement a dict as a splay
tree, and have values() return them nearest-first. This would mean
that just reading from the dictionary could change the order of
values(), yet it wouldn't make the implementation non-conformant.

Of course, if I want splay tree semantics, I'd rather explicitly ask
for that. But it'd be legal.

ChrisA

Thread

dict: keys() and values() order guaranteed to be same? Henrik Faber <hfaber@invalid.net> - 2012-07-23 13:23 +0200
  Re: dict: keys() and values() order guaranteed to be same? Philipp Hagemeister <phihag@phihag.de> - 2012-07-23 13:40 +0200
    Re: dict: keys() and values() order guaranteed to be same? Henrik Faber <hfaber@invalid.net> - 2012-07-23 14:19 +0200
  Re: dict: keys() and values() order guaranteed to be same? Stefan Behnel <stefan_ml@behnel.de> - 2012-07-23 13:43 +0200
  Re: dict: keys() and values() order guaranteed to be same? Stefan Behnel <stefan_ml@behnel.de> - 2012-07-23 13:58 +0200
    Re: dict: keys() and values() order guaranteed to be same? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-23 15:20 +0000
      Re: dict: keys() and values() order guaranteed to be same? Chris Angelico <rosuav@gmail.com> - 2012-07-24 02:18 +1000
      Re: dict: keys() and values() order guaranteed to be same? Ethan Furman <ethan@stoneleaf.us> - 2012-07-26 14:06 -0700
      Re: dict: keys() and values() order guaranteed to be same? Ethan Furman <ethan@stoneleaf.us> - 2012-07-26 14:03 -0700

csiph-web