Python Programming with the Java™ Class Libraries: A Tutorial for Building Web and Enterprise Applications with Jython

The Danger of Exceptions

An unhandled exception can stop a program dead in its tracks. This may be okay if you're still developing it, but it's bad if the program has been delivered. Consider the following function (from divby()-1.py), which stops as soon as it runs into a 0 value as a denominator in the list.

def figurePercentage(figures):
      for tuple in figures:
            numerator = tuple[0]
            denominator = tuple[1]
            percent = numerator/denominator
            print ("The percentage is " + `percent`)

Here the function figurePercentage() expects to receive a sequence of sequences that each contain two numeric fields. So we create a list sequence that contains several tuples, each containing two numeric values, and we invoke figurePercentage() with the sequence as follows: ...