"refactor refactor refactor your code." What does this mean exactly and why do it?

Question

I often heard from professionals blog something like refactoring your code whenever the chance you get. What is it exactly? Rewriting your code in simpler and fewer lines? What is the purpose of doing this?

Answer 1

Refactoring code is a process of cleaning up your code, reducing the clutter and improving the readability without causing any side effects or changes to features.

Basically, you refactor by applying a series of code change rules that improve code readability and re-usability, without affecting the logic.

Always unit test before and after refactoring to ensure your logic isn't affected.

Answer 2

This Wikipedia article will give you an idea of the types of things included in the general concept of Refactoring.

The idea is adapt / evolve your code as you go. Simple things may be to rename variables or method parameters, but others may be to pass an additional parameter or to drop one, or to change its type. The data model may evolve as well. etc.

Often refactoring, works hand-in-hand with unit-testing, whereby the risk of "breaking something" is offset by the fact that such an issue may likely be discovered by the automatic testing (provide a good coverage and relevant test cases...).

In a nutshell, the ability to refactor (and btw, most IDE or add-ons to the IDEs, offer various tools that make refactoring easier and less error prone) allows one to write more quickly without stressing about some decisions ("should this object include an array or a list etc...) letting the programmer change some of these decisions as times goes, and with the added insight offered by having a workable, if not perfect solution. See a related concept: agile development.

Beware, refactoring doesn't give you license to start coding without putting any thought in design, in the object model, the APIs etc., however it lessens the stiffness of some of these decisions.