What does good code look like? In this InfoQ interview, Kent Beck gets questions about his new book, Implementation Patterns, that deals with this very question. Kent talks about the core of the book, explains that the canonical example is Compose Method and describes why that pattern is so important.
You have to work at composing the methods which is why they‘re “for free” in quotes, but once you’ve done it people can read an understand what you have done, people can extend what you’ve done more easily, people can modify what you’ve done more easily and it’s easier to eliminate duplication, because of these little bits of functionality where the way you compute X is these 2 or 3 operators. If that’s in a method somewhere then it’s easy to change, the assumptions in one place is easy to change. If you just say, that is just going to be a one line method what’s the point of making it into a method of its own then you get this proliferation of the design information that assumption that “here’s how you compute…” whatever it is goes a bunch of places in your code and if you want to change it you’re stuck. So for me the central pattern in the book is Compose Method. There is 76 other ones, they are obviously really important or I wouldn’t have put them in, but that is the one that’s kind of the heart of it.
InfoQ’s Amr Elssamadisy reviewed the book when it came out and he concluded:
This is a book that is useful for both junior as well as senior developers - each will come away with something different. Those new to software development will see development through the eyes of one of the most talented developers today. Others with more experience will be able to reflect on why they do things the way they do - practices take on a different meaning by focusing on why they are done. Finally, tying the values and principles (but especially the values) to software development makes everything different - in a very good way.
In the interview, Kent also talks about the relationship between implementation patterns and XP, how patterns came into the software industry and various other things such as his view of the current state of the patterns community and why he believes that the Shu-Ha-Ri description of learning which Alistar Cockburn uses, is naïve and simplistic.
View the 30-minute InfoQ exclusive interview with Kent Beck on Implementation Patterns.