Ask HN: How best to learn software design principles?

Design patterns are the greatest tool there is for learning software design. If you know them, you can apply them, but much more importantly they show you how you can apply the basic principles of OO development to various problems. By learning them, you're learning the thought process of how they came to be, and you'll be able to apply those thought processes to your own problems. Consider it like learning algebra by doing exercises. You can read theory all you like, but unless you apply it it just won't click.

http://martinfowler.com/design.html is also good.

"Architects look at thousands of buildings during their training, and study critiques of those buildings written by masters. In contrast, most software developers only ever get to know a handful of large programs well—usually programs they wrote themselves—and never study the great programs of history. As a result, they repeat one another's mistakes rather than building on one another's successes.

"Our goal is to change that. In these two books, the authors of four dozen open source applications explain how their software is structured, and why. What are each program's major components? How do they interact? And what did their builders learn during their development? In answering these questions, the contributors to these books provide unique insights into how they think.

"If you are a junior developer, and want to learn how your more experienced colleagues think, these books are the place to start. If you are an intermediate or senior developer, and want to see how your peers have solved hard design problems, these books can help you too."

edit: a major advantage to aosa is that all the source is available.