Design Patterns: Elements of Reusable Object-Oriented Software

This book characterizes the kind of thinking that moves you from the low-level 'small' view of a software developer to the high level long-term view of a software architect.While entry-level and junior developers may spent hours arguing fruitlessly over whether OOP is dead or alive, or whether functional programming is better or worse, most senior engineers and software architects are able to use many different paradigms. They understand that these patterns are deeper than the paradigm they are implemented in.They understand that the concepts and ideas underlying these design patterns cannot and will not ever die because they express evergreen solutions to dealing with evolving software systems.Javascript made the prototype pattern its object model. Generators (and coroutines) that make async/await possible are often implemented as combinations of Factories and Iterators. The Observer pattern underlies almost every single reactive UI framework and most micro-service architectures. Decorators have become mainstays in most languages, inversion of control (IoC) is crucial for dependency injection patterns (Angular, etc.), and on and on... In short... these patterns are used absolutely everywhere, yes, even today.Basically, anyone who says these patterns are dead is either profoundly confused or unaware of how prevalent they are underneath everything they do.For those who say you don't need to know the patterns themselves because they are implemented as language features in modern languages... I would say that coders are generally afraid to use what they don't understand. Have you ever seen someone try to do reactive state management well who didn't understand the Observer pattern? It's not pretty. Moreover, there is no language that offers every single one of these patterns as first-class objects, and certainly no language that has them tailor-made for your use case and your business logic.Understanding the problems that these design patterns solve will help you design better software systems no matter what language or framework you use. Understanding how they work is crucial to using them well and not taking the pros and cons of these abstractions for granted.Yes, the examples are in C++ and quite old, and I wish they updated this book to implement these patterns in a newer language like Python, Typescript, Go, Carbon, Kotlin, or C#... but even this slight deficiency doesn't justify taking a star away. Every other part of the book is complete gold. It should be updated, but even this version is well-worth the money.

Twenty Two years since the book's publication it remains incredibly relevant. In the beginning I was surprised the discussion in 1994 was this high level. The preface and introduction are awesome. For example, there was one discussion about dynamically typed languages versus statically typed lanugages... I was not even aware this was being discussed in 1994.In certain situations you see how this book changed the way the field of computer science developed. Before the writing of the book the authors originally called the Singleton pattern the Solitaire pattern. They changed it last minute (explained in the Conclusion) from Solitaire to Singleton, and that is a major part of why everybody calls it Singleton today.Some people may have an issue with the age of book. When you read the introduction, they mention that C++ and Smalltalk are cutting edge programming languages. I know C++ pretty well, but I have never used Smalltalk. What I learned from the book was how Smalltalk was fundamental to creating the MVC (Model-View-Controller) framework. In a lot of places the authors point out situations where C++ programmers would implement a pattern one way, and Smalltalk programmers might use the pattern another way.The book's examples are mostly about text writing programs, windowing, and drawing. These examples fit well for the patterns. You can also see how the current state of programming was much different. Text editors were creating huge innovations back then.This book requires sophistication as a programmer. It will be a challenging book for pretty much anyone to understand completely. You need to have familiarity with the word choice as well. The authors assume you are well versed in their language. The glossary was pretty good in this book, I would recommend taking a look before you start.The progression of the book is excellent. There is a lengthy introduction before getting to the patterns. This helps put the entire book in context and prepares you for the challenge to come. Each pattern is unique in subtle ways that the authors explain masterfully.One hundred years from now this book will still work. The patterns are fundamental to software design itself. I wish most authors were this bold.