I was fortunate to attend Kent Beck’s lecture summarizing his experiences and thoughts regarding efficient software design. Traditionally there have been two schools of thought about design: Predictive design, trying to design everything upfront (and making lot of wrong decisions) and reactive design, where any design is only done if it is absolutely necessary for implementing a feature (thus developing often on top of an insufficient design). Kent tried hard to discover such a design method that really delivers on the promises of both while avoiding their failures. This method is based on evolving design frequently in small, safe steps and focusing on learning while following some key best practices. It doesn’t really matter what scope of design we are are speaking about, the method and principles are the same whether you’re redesigning a class or a complex system.