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Thu Apr 28 22:48:48 CEST 2011 · https://mail.python.org/pipermail/python-dev/2011-April/111072.html

On 4/28/2011 12:55 PM, Guido van Rossum wrote:

> *If* my proposal gets accepted, there will be a blanket rule that no
> matter how exotic an type's __eq__ is defined, self.__eq__(self)
> (i.e., __eq__ called with the same *object* argument) must return True
> if the type's __eq__ is to be considered well-behaved;

This, to me, is a statement of the obvious ;-), but it should be stated 
in the docs.

Do you also propose to make NaNs at least this well-behaved or leave 
them ill-behaved?

 > and Python
> containers may assume (for the purpose of optimizing their own
> comparison operations) that their elements have a well-behaved __eq__.

This almost states the status quo of the implementation, and the doc 
needs to be updated correspondingly. I do not think we should let object 
ill-behavior infect containers, so that they also become ill-behaved 
(not equal to themselves).

-- 
Terry Jan Reedy

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