refactoring.md

Code Smells

• Long Method
• Large Class
• Feature Envy
• Case/Switch Statement
• High Fan-out
• Shotgun Surgery
• Divergent Change
• Long Parameter List
• Duplicated Code
• Uncommunicative Name
• Single Table Inheritance (STI)
• Parallel Inheritance Hierarchies
• Comments
• Mixin
• Callback

Solutions

• Replace Conditional with Polymorphism
• Replace conditional with Null Object
• Extract method
• Rename Method
• Extract Class
• Extract Value Object
• Extract Decorator
• Extract Partial
• Extract Validator
• Introduce Explaining Variable
• Introduce Observer
• Introduce Form Object
• Introduce Parameter Object
• Use class as Factory
• Move method
• Inline class
• Inject dependencies
• Replace Subclasses with Strategies
• Replace mixin with composition
• Replace Callback with Method
• Use convention over configuration
• Introduce Visitor

Principles

• DRY
• Single responsibility principle
• Tell, Don’t Ask
• Law of Demeter
• Composition over inheritance
• Open/closed principle
• Dependency inversion principle