On Tue, Apr 19, 2011 at 4:23 PM, Kushal Kumaran <kushal.kumaran+pyt...@gmail.com> wrote: >> if a + b + c + d != 1: >> raise ValueError("Exactly one of a, b, c or d must be true.") >> > > Unless you're sure all of a, b, c, and d are boolean values, an int > with a negative value slipping in could result in the sum equaling 1, > but more than one of the variables evaluating to True in boolean > contexts.
If they're all expressions, then you can easily guarantee that. ChrisA -- http://mail.python.org/mailman/listinfo/python-list