mwql wrote: > It's really strange, > > if > a = 1 > b = 1 > a is b ==> True > > the same thing applies for strings, but not for dict, lists or tuples > I think the 'is' operator is useful for objects only, not for primitive > types, > I think I solved the mystery behind my bugged code =)
The reason that "is" works for small numbers is that these are cached for performance reasons. Try >>> a = 1000000 >>> b = 1000000 >>> a is b False So - your conclusion is basically right: use is on (complex) objects, not on numbers and strings and other built-ins. The exception from the rule is None - that should only exist once, so foo is not None is considered better style than foo == None. Diez -- http://mail.python.org/mailman/listinfo/python-list
