Lie Ryan wrote: > Tim Harig wrote: >>> Speaking only to the style issue, when I've wanted to do something like >>> that, I find: >>> if self.higher is None is self.lower: >>> more readable, by making clear they are both being compared to a >>> constant, rather than compared to each other. >> By comparing them to *any* constant with 'is' you end up with the same >> potential problems as to whether something with a value of None is actually >> None? > > Oh really? None is a Singleton and all None always point to the same > None object. And the fact that it is impossible to override `is` > operator is the reason for the "is None" idiom. >
http://docs.python.org/c-api/none.html -- http://mail.python.org/mailman/listinfo/python-list