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Groups > comp.lang.python > #45234
| From | Alister <alister.ware@ntlworld.com> |
|---|---|
| Subject | Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] |
| Newsgroups | comp.lang.python |
| References | <mailman.1603.1368401007.3114.python-list@python.org> |
| Message-ID | <HP2kt.66723$Tl3.12499@fx29.fr7> (permalink) |
| Organization | virginmedia.com |
| Date | 2013-05-13 09:59 +0000 |
On Mon, 13 May 2013 05:23:16 +0600, Mr. Joe wrote:
> I seem to stumble upon a situation where "!=" operator misbehaves in
> python2.x. Not sure if it's my misunderstanding or a bug in python
> implementation. Here's a demo code to reproduce the behavior -
> """
> # -*- coding: utf-8 -*-
> from __future__ import unicode_literals, print_function
>
> class DemoClass(object):
> def __init__(self, val):
> self.val = val
>
> def __eq__(self, other):
> return self.val == other.val
>
> x = DemoClass('a')
> y = DemoClass('a')
>
> print("x == y: {0}".format(x == y))
> print("x != y: {0}".format(x != y))
> print("not x == y: {0}".format(not x == y))
> """
>
> In python3, the output is as expected:
> """
> x == y: True x != y: False not x == y: False """
>
> In python2.7.3, the output is:
> """
> x == y: True x != y: True not x == y: False """
> Which is not correct!!
>
> Thanks in advance for clarifications.
> Regards,
> TB
this looks to me like an issue with operator precidence
you code is evaluating as (Not x) == y
rather than not (x == y)
why the difference between 2.7 & 3.X is beyond my knowledge of the
language
The other explanations seem to detail things at low level but it is all
Greek to me
--
Nice guys finish last.
-- Leo Durocher
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Differences of "!=" operator behavior in python3 and python2 [ bug? ] "Mr. Joe" <titanix88@gmail.com> - 2013-05-13 05:23 +0600
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Alister <alister.ware@ntlworld.com> - 2013-05-13 09:59 +0000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Fábio Santos <fabiosantosart@gmail.com> - 2013-05-13 18:26 +0100
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Ned Batchelder <ned@nedbatchelder.com> - 2013-05-13 14:08 -0400
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Chris Angelico <rosuav@gmail.com> - 2013-05-14 04:15 +1000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Fábio Santos <fabiosantosart@gmail.com> - 2013-05-13 19:28 +0100
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Alister <alister.ware@ntlworld.com> - 2013-05-13 21:17 +0000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Fábio Santos <fabiosantosart@gmail.com> - 2013-05-13 22:48 +0100
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-05-13 23:53 +0100
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Dave Angel <davea@davea.name> - 2013-05-13 19:22 -0400
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-14 05:09 +0000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-14 19:01 -0400
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-15 00:15 +0000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-14 22:20 -0400
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Andrew Berg <bahamutzero8825@gmail.com> - 2013-05-13 18:27 -0500
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Ian Kelly <ian.g.kelly@gmail.com> - 2013-05-13 17:32 -0600
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-14 05:21 +0000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Alister <alister.ware@ntlworld.com> - 2013-05-15 14:41 +0000
Re: Differences of "!=" operator behavior in python3 and python2 [ bug? ] Chris Angelico <rosuav@gmail.com> - 2013-05-14 17:31 +1000
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