14.2. Exceptions in Python

The remaining sections of this chapter talk specifically about the exception mechanisms built into Python. The entire Python exception mechanism is built around an object-oriented paradigm, which makes it both flexible and expandable. If you aren’t familiar with OOP, you don’t need to learn OO techniques in order to use exceptions.

Like everything else in Python, an exception is an object. It’s generated automatically by Python functions with a raise statement. After it’s generated, the raise statement, which raises an exception, causes execution of the Python program to proceed in a manner different than would normally occur. Instead of proceeding with the next statement after the raise, or whatever generated the exception, the current call chain is searched for a handler that can handle the generated exception. If such a handler is found, it’s invoked and may access the exception object for more information. If no suitable exception handler is found, the program aborts with an error message.