On Sat, Jul 12, 2008 at 4:01 PM, Dick Moores <[EMAIL PROTECTED]> wrote: > _Python in a NutShell_, p. 138 has a bit on the assert statement which I > don't completely understand. > > It says the syntax is > > assert condition[, expression] > > I was hoping to put some sort of explanation of failure in an assert > statement. But how to do it? > > In my code I have > > assert(len(list(set(colors_used_this_cycle))) == > len(colors_used_this_cycle), "A color has been used twice!")
Leave out the outermost parentheses, assert is a statement, not a function call. In [2]: assert(False, "Asserted false") This is "assert condition" where the condition is a tuple with two elements, hence true so there is no output. In [3]: assert False, "Asserted false" --------------------------------------------------------------------------- <type 'exceptions.AssertionError'> Traceback (most recent call last) /Users/kent/<ipython console> in <module>() <type 'exceptions.AssertionError'>: Asserted false This is the form with an optional expression and works the way you want. Kent _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
