Refactoring

UserPreferences

What is it?

• Programmers restructure the system without changing its behavior to remove duplication, improve communication, simplify, or add flexibility.
• improving the design without changing functionality
• improving communication, simplicity, flexibility
• removing duplication
• removing bad code-smells

Example Refactorings:

• combine or split classes
• rename method, variable, class
• migrate method up or down inheritance
• move block of code to method

Refactorings themselves not rocket science... but knowing how to refactor toward SimpleDesign takes experience.

Benefits:

• makes code easier to understand and modify
• makes it easier to find bugs
• makes it easier for the next person
• you might be the next person
• ===> faster development

Why should I refactor if my code works?

• to reverse entropy
• to make it simple
• to make it easy to extend
• to make it clean

If this is a "best practice", then why don't people do it?

• schedule pressure
• actually, well-refactored code makes programmers faster
• short-timer attitudes
• management doesn't understand, doesn't permit
• coders don't understand the code well enough to refactor it
• coders don't know how to do one tiny refactoring at a time
• no tests

How is it any different if done "eXtreme"?

• done very frequently in tiny tiny steps

What other practices support this practice?

• CommonVocabulary helps us see problem spots, spot smells
• SustainablePace makes us be rested and make fewer mistakes
• SimpleDesign is always easier to work with
• UnitTesting provides a safety net
• PairProgramming gives the courage to refactor, encourages refactoring, and makes it more safe
• CollectiveOwnership puts more eyes on the code and encourages more refactoring all over the system
• ContinuousIntegration's automated build/test process lets us know if break something
• CodingStandards helps us focus on the task at hand

What other practices are supported by this one?

• relieves us from the need to construct a SimpleDesign the first time
• moves the code toward SimpleDesign
• makes UnitTesting easier
• makes PairProgramming more fun
• smaller pieces reduce chance of conflicts with CollectiveOwnership

How do I get started?

• Read Fowler's Refactoring book and http://www.refactoring.com/
• Take William Wake's refactoring challenge: http://xp123.com/

Next: PairProgramming

-- AndrewFuqua, JohnMHammer - 31 Mar 2002