Differences of "!=" operator behavior in python3 and python2 [ bug? ]

Date	2013-05-13 05:23 +0600
Subject	Differences of "!=" operator behavior in python3 and python2 [ bug? ]
From	"Mr. Joe" <titanix88@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.1603.1368401007.3114.python-list@python.org> (permalink)

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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

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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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