On Wed, Oct 15, 2008 at 11:03 AM, Terry Reedy <tjreedy@udel.edu> wrote:
> George Sakkis wrote:
>>
>> Now that 3.x fixes the arbitrary object comparison wart and drops (?)
>> __cmp__,
>
> An entry for __cmp__ was in the 3.0c1 doc, which confused me.
> It is now gone in
> http://docs.python.org/dev/3.0/reference/datamodel.html#special-method-names
>
> Since rich comparisons are defined on object and are inherited by all
> classes, it would be difficult to make them not defined.

I should also note that part of George's proposal has already been
implemented: if you define __eq__, you get a complementary __ne__ for
free. However it doesn't work the other way around (defining __ne__
doesn't give you __eq__ for free), and there is no similar
relationship for the ordering operators. The reason for the freebie is
that it's *extremely* unlikely to want to define != as something other
than the complement of == (the only use case is IEEE compliant NaNs);
however it's pretty common to define non-total orderings (e.g. set
inclusion).