Refactoring: Improving the Design of Existing Code

Chapter 9Organizing Data

Data structures play an important role in our programs, so it’s no great shock that I have a clutch of refactorings that focus on them. A value that’s used for different purposes is a breeding ground for confusion and bugs—so, when I see one, I use Split Variable (240) to separate the usages. As with any program element, getting a variable’s name right is tricky and important, so Rename Variable (137) is often my friend. But sometimes the best thing I can do with a variable is to get rid of it completely—with Replace Derived Variable with Query (248).

I often find problems in a code base due to a confusion between references and values, so I use Change Reference to Value (252) and Change Value to Reference (256) to change ...