Chapter 7. Working with Functions

Functions are at the heart of a well-organized script, and will make your code easy to read and reuse. No large project would be manageable without them, as the problem of repetitive code would bog down the development process. Throughout this chapter, we will investigate functions and demonstrate some of the ways in which they can save you from repetitive work. In this chapter, you will learn

• How to define and call functions from within your scripts

• How to pass values to functions and receive values in return

• How to call a function dynamically using a string stored in a variable

• How to access global variables from within a function

• How to give a function a "memory"

• How to pass data to functions by reference

• How to create anonymous functions

• How to verify that a function exists before calling it