[Python-Dev] PyObject_RichCompareBool identity shortcut

[Nick Coghlan]

On Fri, Apr 29, 2011 at 8:55 AM, Guido van Rossum <guido at python.org> wrote:
> Sorry, we'll have to make an exception for those of course. This will
> somewhat complicate the interpretation of well-behaved, because those
> are *not* well-behaved as far as containers go (both dict key lookup
> and list membership are affected) but it is not a bug -- however it is
> a bug to put these in containers and then use container comparisons on
> the container.

That's a point in favour of the status quo, though - with the burden
of enforcing reflexivity placed on the containers, types are free to
make use of rich comparisons to return more than just simple
True/False results.

I hadn't really thought about it that way before this discussion - it
is the identity checking behaviour of the builtin containers that lets
us sensibly handle cases like sets of NumPy arrays.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia