Core Python Programming

10.4. *Exceptions as Strings

Prior to Python 1.5, standard exceptions were implemented as strings. However, this became limiting in that it did not allow for exceptions to have any relationships to each other. With the advent of exception classes, this is no longer the case. As of 1.5, all standard exceptions are now classes. It is still possible for programmers to generate their own exceptions as strings, but we recommend using exception classes from now on.

For backwards compatibility, it is possible to revert to string-based exceptions. Starting the Python interpreter with the command-line option -X will provide you with the standard exceptions as strings. This feature will be obsoleted beginning with Python 1.6.

If you must use string exceptions, ...