Applied Software Project Management

Refactoring

To refactor a program is to improve the design of that program without altering its behavior.^[*] There are many different kinds of improvements—called refactorings— that can be performed.

Every programmer knows that there are many ways to write code to implement one specific behavior. There are many choices that do not affect the behavior of the software but that can have an enormous impact on how easy the code is to read and understand. The programmers choose variable names, decide whether certain blocks of code should be pulled out into separate functions, choose among various different but syntactically equivalent statements, and make many other choices that can have a significant impact on how easy the software is to maintain.

Many programmers think of coding as a purely constructive task, for which the only reason to add, remove, or change the source code is to alter the behavior of the software. Refactoring introduces a new concept: adding, removing, or changing the source code for the sole purpose of making it easier to maintain. There are many different refactorings, or techniques, through which programmers can alter their code to make it easier to understand.

Refactoring is a new way of thinking about software design. Traditionally, software is designed first and then built. This is especially true of object-oriented programming, where the programmers might be handed a complex object model to implement. But most programmers who have worked on a reasonably complex ...