Kiuhnm <kiuhnm03.4t.yahoo.it> writes: > I can't think of a single case where 'is' is ill-defined.
If I can't predict the output of print (20+30 is 30+20) # check whether addition is commutative print (20*30 is 30*20) # check whether multiplication is commutative by just reading the language definition and the code, I'd have to say "is" is ill-defined. > You're blaming 'is' for revealing what's really going on. 'is' is > /not/ implementation-dependent. It's /what's going on/ that's > implementation-dependent. > "a is b" is true iff 'a' and 'b' are the same object. Why should 'is' > lie to the user? Whether a and b are the same object is implementation-dependent. -- http://mail.python.org/mailman/listinfo/python-list