Chapter 9. Handlers

A handler is a subroutine within a script. A handler is an important form of flow control, and leads to better-behaved, better-organized, more reusable, and more legible code. With a handler, the same code can be executed from different places in a script. Even if a handler is going to be called only once in the course of a script, it's a useful organizational device because it names a block of code, and this name can describe the block's purpose.