[Python-Dev] Equality on method objects

[Armin Rigo]

Hi all,

In Python 2.5, I made an attempt to make equality consistent for the
various built-in and user-defined method types.  I failed, though, as
explained in http://bugs.python.org/issue1617161.  The outcome of this
discussion is that, first of all, we need to decide which behavior is
"correct":

    >>> [].append == [].append
    True or False?

(See the issue tracker for why the answer should probably be False.)

The general question is: if x.foo and y.foo resolve to the same method,
should "x.foo == y.foo" delegate to "x == y" or be based on "x is y"?

The behavior about this has always been purely accidental, with three
different results for user-defined methods versus built-in methods
versus method wrappers (those who know what the latter are, raise your
hand).

(Yes, Python < 2.5 managed three different behaviors instead of just
two: one of the types (don't ask me which) would base its equality on
the identity of the 'self', but still compute its hash from the hash of
'self'...)


A bientot,

Armin