refactoring-techniques

name	refactoring-techniques
description	Refactoring techniques for improving code maintainability. Use when refactoring code to reduce complexity and apply SOLID principles.
license	Apache 2.0

Refactoring Techniques

When to Use This Skill

• Refactoring code
• Reducing complexity
• Applying SOLID principles

Core Concepts

Extract Method

// Before: Long method
async function processOrder(order) {
  // Validate order (20 lines)
  // Calculate total (15 lines)
  // Charge payment (10 lines)
  // Update inventory (10 lines)
  // Send confirmation (5 lines)
}

// After: Extracted methods
async function processOrder(order) {
  validateOrder(order);
  const total = calculateTotal(order);
  const paymentResult = await chargePayment(order, total);
  await updateInventory(order);
  await sendConfirmation(order);
}

Move Method

// Before: Feature envy
class Report {
  generate(order) {
    const total = order.items.reduce((sum, item) => 
      sum + (item.price * item.quantity), 0);
  }
}

// After: Method moved to data owner
class Order {
  getTotal() {
    return this.items.reduce((sum, item) => 
      sum + (item.price * item.quantity), 0);
  }
}

Replace Primitive with Class

// Before: Primitive obsession
class Order {
  constructor(public email: string) {
    if (!email.includes('@')) throw new Error('Invalid');
  }
}

// After: Value Object
class Email {
  constructor(public value: string) {
    if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(value)) {
      throw new Error('Invalid email');
    }
  }
}

Common Scenarios

Long Method

• Extract smaller methods
• Name methods clearly

Large Class

• Identify responsibilities
• Extract classes

Duplicate Code

• Extract to shared method
• Replace duplicates

References

• Refactoring - Martin Fowler