Timothy A. Budd - An Introduction to Object-Oriented Programming

When I began writing my first book on Smalltalk in 1983, I distinctly remember thinking that I must write quickly so as to not miss the crest of the object-oriented programming wave. Who would have thought that two decades later object-oriented programming would still be going strong? And what a long, strange trip it has been.

In the two decades that object-oriented programming has been studied, it has become the dominant programming paradigm. In the process, it has changed almost every facet of computer science. And yet I find that my goal for the third edition of this book has remained unchanged from the first. It is still my hope to impart to my students and, by extension, my readers an understanding of object-oriented programming based on general principles and not specific to any particular language.

Languages come and go in this field with dizzying rapidity. In the first edition I discussed Objective-C and Apples version of Object Pascal, both widely used at that time. Although both languages still exist, neither can at present be considered a dominant language. (However, I talk about Objective-C in the third edition because from a language point of view it has many interesting and unique features.) Between the first edition and the third many languages seem to have disappeared (such as Actor and Turing), while others have come into existence (such as Java, Eiffel, and Self). Many existing languages have acquired object extensions (such as Common Lisp and Object Perl), and many have burst onto the scene for a short while and then just as suddenly disappeared (for example, Sather and Dylan). Then there is Beta, a language that hints at wonderful ideas behind an incomprehensible syntax. Prediction is difficult, particularly about the future. Will languages that are just now appearing, such as Ruby, have staying power, or will they go the way of Dylan? What about C#? It is difficult to imagine that any language with Microsoft behind it will fail to be successful, but stranger things have happened. (Personally, I think that C# will last because it presents a route for Visual Basic programmers to finally progress to a better language, but that few Java or C++ programmers will migrate to the new language. Time will tell if my powers of foresight are any better than anybody elses.)

For the present edition I have expanded the number of languages that I use for examples, but I have eliminated many long narratives on a single language. Descriptions of techniques are often given in the form of tables or shorter explanations. As with the first two editions, I make no pretenses of being a reference manual for any language, and students producing anything more than trivial programs in any of the languages I discuss would do well to avail themselves of a language-specific source.

Nevertheless, in this third edition I have attempted to retain the overall structure I used in the first two editions. This can be described as a series of themes.

I. Introduction and Design. , are used in problem solving. The manipulation of physical index cards in a group setting is one of the best techniques I have encountered for developing and reinforcing the notions of behavior, responsibility, and encapsulation.

In the past decade the field of object-oriented design has expanded considerably. And for many readers may either be too little or too muchtoo much if they already have extensive experience with object-oriented modeling languages and design, and too little if they have never heard of these topics. Nevertheless, I have tried to strike a balance. I have continued to discuss responsibility-driven design, although it is now only one of many alternative object-oriented design techniques, because I think it is the simplest approach for beginning students to understand.