Excuse my long absence from blogging, but I have a good excuse: I’ve been hard at work on my Scala Refactoring project.

Today, I’m going to show you how you can implement your very own automated refactoring for Scala. “Implement a refactoring you say? But I don’t use IDE xy!”. Don’t worry, you won’t have to use a specific IDE, in fact, you don’t need to use an IDE at all.

Why should you want to write a refactoring? IDEs usually provide a bunch of general refactorings and code generators, but maybe you need a framework or project specific one that no IDE will implement for you. And don’t worry, it is not as complicated as it might sound. (And I should add that when I write refactoring, this includes all program transformations that affect the source code, so you could also create a transformation that just creates new code.)

A refactoring is essentially a transformation of the program in its tree form. Unfortunately, our programs are stored in plain text files, so the transformed tree has to be converted back to text, and this without losing all our pretty formatting. One of the design goals of the Scala Refactoring library was to separate these two concerns as good as possible, so that the implementor (you!) of a refactoring can concentrate on transforming trees and let the library do all the ugly code generation for him. To make it easier for those who already know the Scala compiler’s abstract syntax tree, the refactorings are completely based on this AST instead of introducing a new program representation. I can’t introduce Scala’s AST in detail here, but there’s an introduction in my term project’s technical report which I also plan to expand in my master’s thesis (please give me feedback if you notice any errors).

Please continue reading the rest of the post on my project wiki (where the layout is much more suited for source code).