[Python-Dev] == on object tests identity in 3.x
benjamin at python.org
Mon Jul 7 17:15:47 CEST 2014
On Mon, Jul 7, 2014, at 04:22, Andreas Maier wrote:
> While discussing Python issue #12067
> (http://bugs.python.org/issue12067#msg222442), I learned that Python 3.4
> implements '==' and '!=' on the object type such that if no special
> equality test operations are implemented in derived classes, there is a
> default implementation that tests for identity (as opposed to equality
> of the values).
> The relevant code is in function do_richcompare() in Objects/object.c.
> IMHO, that default implementation contradicts the definition that '=='
> and '!=' test for equality of the values of an object.
> Python 2.x does not seem to have such a default implementation; == and
> != raise an exception if attempted on objects that don't implement
> equality in derived classes.
Why do you think that?
Python 2.7.6 (default, May 29 2014, 22:22:15)
[GCC 4.7.3] on linux2
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>>> class x(object): pass
>>> class y(object): pass
>>> x != y
>>> x == y
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