12 - Objects and Classes – Objects Are in a Class By Themselves

Summary

VB Quip

But what is it good for? – an engineer at the Advanced Computing Systems Division of IBM, commenting on the microchip in 1968

Think of objects as tools. Better yet, think of them as building blocks. Imagine how hard a job would be if you had to create everything from scratch every time. Say you wanted to build a table. First, you'd need to make an axe to cut down the tree. Then you'd have to make a saw to cut the wood. You'd have to make your own nails to piece together the table, but that's only after you made your own hammer so you could pound the nails. Programming is like that sometimes – OK, usually. And it was certainly that way years ago. Everything was done from scratch and very little was reusable. However, there's been some progress since then. You saw reusable code when you learned procedures and functions. Objects and classes are that way, but on a grander scale. The controls in the Toolbox are objects, each specially created for a specific task. They're tools and, without them, development would be much tougher, and a whole lot less fun. Classes are code that defines an abstract data type – it's a thing, and the developer provides a description of it and determines how it can be used. This chapter shows you how to create objects with your code and how to define and use classes.