Introduction
Computers have come a long way since the days of huge gigantic machines spanning multiple rooms. These
days we have sleek computers have more computing power than the old giants put together. All along in this journey
Software has also undergone huge changes.
Starting from the days of Assembly
programming to structural programming to modular programming to Object oriented programming (OOPS). All these development was restricted to the ordering of the code, but once OOPS became popular the thrust was more on reusable object components and identifying similar patterns used over and over at various places. These patterns are known as Design Patterns. Elements of Reusable Object-Oriented Software was one of the first and also one of the better books to come out on this topic.
About the book
The book is all about Design Patterns and starts by explaining what Design Patterns are and how is the identification of them going to be useful in the software development cycle. The first few chapters consist of identifying patterns, using patterns and software development around patterns.
Once the reason for patterns is cleared, the book moves on to the various patterns themselves. The patterns have been classified as Creational Patterns, Structural Patterns and Behavioural Patterns. A few patterns in each of these categories are described.
The description of the patterns is in a very organized manner. The description contains the synonyms for the pattern, the motivation behind the pattern, the applicability of the pattern, the structure of the pattern, the participants, the collaborations, the consequences, the Implementation, sample code and known uses.
The book concludes with a note on the community of Design Pattern developers and the history of Design Patterns. The Glossary contains a bit on Class and Object Diagrams and other design details.
Critic's Viewpoint
The book is one of the better books on Design Patterns. It describes each and every pattern in a very detailed manner. As mentioned above it goes behind just telling the definition of the pattern and tells about how to use it and how it is structured.
The foursome authors need to get a pat on the back the way they have logically arranged all the patterns and the information regarding the patterns.
Some of the patterns dealt with are Singleton, Bridge, Adaptor, Factory etc.
But, the foursome just fall short of greatness. For one the code samples and examples could have been better and simpler. Most of the newbies who take up this book drop it like hot potatoes as most of the stuff seems to be going over head. After some experience these same people relish the book like anything!! The reason is very simple, the examples are just not very clear. There is a slight confusion as to how and where exactly this is going to be used.
Again as most of the patterns in a category are similar, the fine line differences don't come up in some of the examples. Thus, if the examples are made better the book becomes too good.
About the Authors
The book is authored by Dr. Erich Gamma, Dr. Richard Helm, Dr. Ralph Johnson and Dr. John Vlissides who are all recognized experts in the field of object oriented software.
The foreword for the book is given by Grady Booch another bigwig in the object oriented world.
Summary
One of the better books on Design Patterns. I would give this book a five starrer, though I would like the examples to be improved slightly.