Chapter 8. Programming, Object-Oriented Technology, and Software Development

Programming is simply the process of telling the computer what to do. In the earliest days, when both the computers and the tasks they could perform were fairly simple, programming was relatively straightforward. It's a good thing, too, since this chore was initially accomplished by flipping switches back and forth. Once paper (card punch) and magnetic storage were available to hold a bunch of instructions at once, people were ready to move beyond the direct input of machine instructions. The evolution of groups of instructions into a language, with a particular syntax and vocabulary, is a fairly obvious development. Still, the people who did early programming language work were a remarkably talented group; when we observe the enormous productive capacity of modern computers, we should be thankful for the ingenuity and determination of these pioneers.

We'll see in this chapter that programming has moved to ever-higher levels of abstraction that can be represented in four distinct levels. The lowest, and conforming directly to the circuitry of the CPU, is machine language. Next, still closely connected to the hardware, is assembly language. The third level, usually called high-level, consists of languages like Cobol, Basic, and C that are more removed from the CPU. This means that they can't get the kind of performance that the lower levels can, but that they are easier to use and can be ported from one system to another. At the highest level, there is acollection of disparate languages, sometimes called "4GL" to reflect their fourth generation status, that are even less efficient but even easier to use and more portable. These include database and markup languages and some of the "visual" programming tools that are now widely used. This chapter will also cover another approach to creating software, called object-oriented programming, that is not so much a different level of language as it is a different way of thinking about writing.

Object-oriented programming, generally called by the more generic term of object-oriented technology (OOT) is one of the hottest topics in computing. From one point of view, this attention isn't justified—objects are simply a special way of describing programming that is highly structured and modular. Many programmers were already writing code that had these qualifications before the OOT craze began. Still, we'll see that there are elements of OOT that, if not unique, are nevertheless given more attention than in traditional programming. Most important, whether OOT is viewed as new or derivative, it's a fact that the use of objects is changing the way people think about programming.

Programming isn't just learning a language, however. After some fifty years of work, software developers have learned a great deal about the most efficient ways to program. Effective programming requires careful planning and a strong sense of discipline. A programmer starting a project today has to do more than choose a language. He or she would be well advised to study programming concepts and to learn the techniques of the masters. This chapter won't teach you to program, but it will give you an understanding of

• Basic programming terminology

• Interpreted vs. compiled languages

• Programming languages by level

• Object-oriented technology

• Problems facing programmers today

• Programming tools and techniques