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From: Pradipto Banerjee <pradipto.banerjee@adainvestments.com>
To: "Python-list@python.org" <Python-list@python.org>
Date: Tue, 16 Oct 2012 08:51:46 -0500
Subject: overriding equals operation
Thread-Topic: overriding equals operation
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Xref: csiph.com comp.lang.python:31402

I am trying to define class, where if I use a statement a =3D b, then inste=
ad of "a" pointing to the same instance as "b", it should point to a copy o=
f "b", but I can't get it right.

Currently, I have the following:

----

class myclass(object):
        def __init__(self, name=3D'')
                self.name =3D name

        def copy(self):
                newvar =3D myclass(self.name)
                return newvar

        def __eq__(self, other):
                if instance(other, myclass):
                        return self =3D=3D other.copy()
                return NotImplemented
----

Now if I try:

>>> a=3Dmyclass()
>>> a.name =3D 'test'
>>> b=3Da
>>> b.name
'test'
>>> b.name =3D 'test2'
>>> a.name
'test2'

I wanted b=3Da to make a new copy of "a", but then when I assigned b.name =
=3D 'test2', even a.name became 'test2'.

How can I rectify my code to make the __eq__() behave like copy()?

Thanks


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