/refactor - Code Refactoring Command for Claude

The /refactor command provides intelligent code refactoring capabilities with multiple strategies and safety checks.

Usage

/refactor [options] <file_or_selection>

Options

Refactoring Types

• --extract-function - Extract repeated code into functions
• --extract-variable - Extract complex expressions into variables
• --extract-constant - Move magic numbers/strings to constants
• --inline - Inline simple functions/variables
• --rename - Rename variables/functions for clarity
• --simplify - Simplify complex conditional logic
• --modernize - Update to modern language features
• --performance - Apply performance optimizations

Safety Options

• --dry-run - Show proposed changes without applying
• --interactive - Prompt for each change
• --backup - Create backup before refactoring
• --test-first - Run tests before and after changes

Language-Specific Options

• --javascript - Apply JS/TS specific refactoring
• --python - Apply Python-specific refactoring
• --java - Apply Java-specific refactoring
• --csharp - Apply C#-specific refactoring

Examples

Extract Function

// Before
function processUsers(users) {
  for (let user of users) {
    if (user.email && user.email.includes("@")) {
      user.isValid = true;
      user.domain = user.email.split("@")[1];
    } else {
      user.isValid = false;
      user.domain = null;
    }
  }
}

// After refactoring with --extract-function
function validateEmail(email) {
  return email && email.includes("@");
}

function extractDomain(email) {
  return email.split("@")[1];
}

function processUsers(users) {
  for (let user of users) {
    if (validateEmail(user.email)) {
      user.isValid = true;
      user.domain = extractDomain(user.email);
    } else {
      user.isValid = false;
      user.domain = null;
    }
  }
}

Extract Constants

# Before
def calculate_discount(price, customer_type):
    if customer_type == "premium":
        return price * 0.2
    elif customer_type == "regular":
        return price * 0.1
    else:
        return 0

# After refactoring with --extract-constant
PREMIUM_DISCOUNT_RATE = 0.2
REGULAR_DISCOUNT_RATE = 0.1
PREMIUM_CUSTOMER_TYPE = "premium"
REGULAR_CUSTOMER_TYPE = "regular"

def calculate_discount(price, customer_type):
    if customer_type == PREMIUM_CUSTOMER_TYPE:
        return price * PREMIUM_DISCOUNT_RATE
    elif customer_type == REGULAR_CUSTOMER_TYPE:
        return price * REGULAR_DISCOUNT_RATE
    else:
        return 0

Modernize Code

// Before (ES5 style)
function getUserNames(users) {
  var names = [];
  for (var i = 0; i < users.length; i++) {
    if (users[i].active) {
      names.push(users[i].name);
    }
  }
  return names;
}

// After refactoring with --modernize
function getUserNames(users) {
  return users.filter((user) => user.active).map((user) => user.name);
}

Refactoring Patterns

Design Patterns

• Strategy Pattern - Replace conditional logic with strategy objects
• Factory Pattern - Extract object creation logic
• Observer Pattern - Implement event-driven architecture
• Decorator Pattern - Add functionality without inheritance

Code Smells Detection

• Long Method - Break down large functions
• Large Class - Split into focused classes
• Duplicate Code - Extract common functionality
• Long Parameter List - Use parameter objects
• Feature Envy - Move methods to appropriate classes

Performance Optimizations

• Lazy Loading - Load resources only when needed
• Memoization - Cache expensive computations
• Batch Operations - Combine multiple operations
• Async Optimization - Convert synchronous to asynchronous

Safety Measures

Pre-refactoring Checks

• Syntax validation
• Type checking (TypeScript, etc.)
• Lint rule compliance
• Test coverage analysis

Post-refactoring Validation

• Automated test execution
• Code quality metrics comparison
• Performance benchmarking
• Security vulnerability scanning

Integration

IDE Integration

• VS Code extension support
• IntelliJ plugin compatibility
• Vim/Neovim integration
• Emacs package support

CI/CD Integration

• Pre-commit hooks
• GitHub Actions workflow
• GitLab CI pipeline
• Jenkins job integration

Configuration

Create a .refactor.json file in your project root:

{
  "rules": {
    "maxFunctionLength": 20,
    "maxParameterCount": 4,
    "enforceConstantExtraction": true,
    "modernizeFeatures": true
  },
  "exclude": ["node_modules/**", "dist/**", "*.test.js"],
  "backup": {
    "enabled": true,
    "directory": ".refactor-backups"
  }
}