[Python-ideas] checking for identity before comparing built-in objects

[Steven D'Aprano]

On Mon, Oct 08, 2012 at 09:29:42AM -0700, Guido van Rossum wrote:

> It's not about equality. If you ask whether two NaNs are *unequal* the
> answer is *also* False.

Not so. I think you are conflating NAN equality/inequality with ordering 
comparisons. Using Python 3.3:

py> nan = float('nan')
py> nan > 0
False
py> nan < 0
False
py> nan == 0
False
py> nan != 0
True

but:

py> nan == nan
False
py> nan != nan
True


-- 
Steven