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Common strategies for improving code structure without changing behavior

Core Idea: Refactoring patterns are systematic approaches to restructuring code that improve design, readability, and maintainability while preserving existing functionality.

Key Elements

• Refactoring involves making incremental, behavior-preserving transformations to code
• Each pattern addresses specific code smells or structural issues
• Effective refactoring requires discipline and appropriate tooling
• Patterns provide a shared vocabulary for discussing code improvements
• Successful refactoring balances short-term costs with long-term benefits

Common Refactoring Patterns

1. Extract Method/Function

   • Moves code fragment into a separate named method
   • Improves readability and reduces duplication
   • Creates potential for reuse

2. Rename Variable/Method/Class

   • Changes identifier to better reflect purpose
   • Improves code readability and self-documentation
   • Crucial for maintaining conceptual integrity

3. Move Method/Function

   • Relocates method to a more appropriate class or module
   • Improves cohesion and reduces coupling
   • Helps maintain single responsibility principle

4. Replace Conditional with Polymorphism

   • Substitutes conditional logic with class hierarchy
   • Makes code more extensible
   • Allows for cleaner type-specific behavior

5. Inline Method/Temp Variable

   • Removes unnecessary abstraction or intermediate variable
   • Simplifies code when abstraction provides no value
   • Often used when unwinding inappropriate abstractions

6. Introduce Parameter Object

   • Groups related parameters into a single object
   • Simplifies method signatures
   • Creates natural home for behavior related to those parameters

When to Refactor

• During regular development as part of normal work
• When adding features to complex areas
• Before fixing bugs to clarify structure
• When code review identifies improvement opportunities
• As dedicated effort when technical debt accumulates

Connections

• Related Concepts: The Wrong Abstraction (a problem that refactoring solves), Recovering from Bad Abstractions (specific refactoring strategy), Technical Debt (motivation for refactoring)
• Broader Context: Software Maintenance (refactoring as maintenance activity), Clean Code Principles (goals of refactoring)
• Applications: Test-Driven Development (tests enable safe refactoring), Continuous Integration (environment for safe refactoring)

References

1. Fowler, Martin. "Refactoring: Improving the Design of Existing Code"
2. Feathers, Michael. "Working Effectively with Legacy Code"

#programming #refactoring #software_design #clean_code

Connections:

Sources:

• From: Article The Wrong Abstraction