>-----Original Message-----
>From: John W. Long [mailto:ws / johnwlong.com]

>When is it a good idea to subclass and create my own error 
>class? 

Your testing example was good, and similarly, it also aids in debugging down
the line. For example, if you have a method that opens a file and
manipulates the data, its generally a good idea to know if an exception
coming out of that method is related to the file ops or due to some use of
the standard library, or from a defined bad operation from your code (error
condition). Defining a derived exception class is a bit safer for client
code to handle, rather than just parsing the exception message.

David