Exceptions: Back to the Future

Once upon a time (well, prior to Python 2.6 and 3.0), it was possible to define exceptions in two different ways. This complicated try statements, raise statements, and Python in general. Today, there is only one way to do it. This is a good thing: it removes from the language substantial cruft accumulated for the sake of backward compatibility. Because the old way helps explain why exceptions are as they are today, though, and because it’s not really possible to completely erase the history of something that has been used by a million people over the course of nearly two decades, let’s begin our exploration of the present with a brief look at the past.