Refactoring Guide Skill
Refactoring is the process of restructuring existing computer code—changing the factoring—without changing its external behavior.
Core Refactoring Patterns
1. Composing Methods
- Extract Method: If a method is too long or complex, turn a fragment of it into its own method.
- Inline Method: If a method body is as clear as its name, move the body into the callers and delete the method.
2. Moving Features Between Objects
- Move Method/Field: Relocate logic to the class where it most naturally belongs to reduce coupling.
3. Simplifying Expressions
- Decompose Conditional: Extract complex conditional logic into clearly named methods.
- Consolidate Conditional Expression: Merge multiple conditional checks that lead to the same result.
4. Clean Code & Naming
- Rename: Use clear, intention-revealing names for variables, methods, and classes.
- Replace Magic Number with Symbolic Constant: Use named constants instead of literal numbers.
Safe Refactoring Workflow
- Verify Tests: Ensure you have a solid test suite that passes before starting.
- Small Steps: Make one tiny change at a time.
- Run Tests: Execute the test suite after every small change to catch regressions immediately.
- Commit Often: Commit your changes once a small refactoring step is complete and verified.
When to Refactor
- Rule of Three: Refactor when you find yourself doing something for the third time.
- Code Smells: Refactor when you encounter long methods, large classes, or duplicated code.
- Adding Features: Refactor before adding new functionality to make the implementation easier.