XLIB Programming Manual, Rel. 5, Third Edition

Chapter 2. X Concepts

This chapter introduces the concepts that underlie X programming. You should read this chapter even if you are the type of person who likes to jump right into the code. (If you are desperate, you can skip ahead to Chapter 3 and return to this chapter when you get confused.) “An hour or so spent reading about the system in general can save many hours of programming that leads to a dead end when the approach turns out to be wrong.”

When learning a new programming language, many programmers prefer to look at a few code samples and then begin programming right away, looking up more information as they need it. This manual is organized so that most of it is useful both as a tutorial and as a reference. There are lots of code samples and fragments in this manual to help the person who likes to read code more than words. Around the code they will find many of the concepts described that are necessary for understanding that particular example.

The “just-look-at-the-examples” approach works up to a point. It allows a sharp individual to get “something” running in a very short time. Eventually, however, programmers find that in order to get the most out of a system—and sometimes even to get it do anything useful—a lot of underlying issues must be understood. In X, there are a lot of interrelated concepts and assumptions that are so basic that the programmer should know them cold. An hour or so spent reading about the system in general can save many hours of programming ...