Designing Object-Oriented Software Book

Considering this book was written before many of the most the popular OO languages like Java, C#, Ruby, Python; even existed, it feels pretty contemporary. It talks heavily about arguably suboptimal concepts like multiple inheritance and getting the upfront design right but I think we can take most of the ideas and apply them to Agile environments, that is, we still do planning on Agile even though incremental, iterative development is at the heart of the process. We don't necessarily have to write a full blown upfront design, but we can use the elaborated techniques described in this book to come up with good, supple and flexible feature/system designs easy to refactor down the road.

Most of these concepts have stood the test of time.

You're presented with notions like who controls what, spreading system intelligence as evenly as possible rather than encapsulating most behaviour in a single class, wrap classes inside subsystems (modules) to reduce coupling and increase cohesion.

The authors thoroughly break down the building blocks of OOP in a way you wish you had learned before you've ever saw an OO language:

- Inheritance is just about factoring out common functionality into a single place.
- Objects communicate with each other by sending messages.
- Messages have a name and may include arguments.
- Objects handle messages by executing methods.
- The set of messages an object can respond to is known as behaviour.
- When two or more kinds of objects can respond to the same message by executing different methods which have the same message name, you get polymorphism.

It was great to read a book from the time when a lot of the stuff we now take for granted had to be factored into the design like: classes for handling Arrays, graphic operations, fixed/floating point numbers, etc. Things we today get from programming frameworks with a rich library of built-in functionality, it gives you an idea of where we're coming from being a refreshing reminder of what things the underlying platform is doing for you.