[Python-Dev] A proposal has surfaced on comp.lang.python toredefine "is"

[Guido van Rossum]

> I can understand why you might be disinclined, but I do see why recursive
> "is" might be cheaper.  The simplest case is probably comparing two
> 2-element tuples, where the elements are arbitrary objects.  == might not
> even be defined on those objects, but "is" would be.

Ah, but that would be definite incompatible change in semantics.  I
would be very suprised if this printed "IS":

a = []
b = []
if (a, b) is (a, b): print "IS"
else: print "ISN'T"

--Guido van Rossum (home page: http://www.python.org/~guido/)