Refactoring

Refactoring

Comprehensive refactoring skill for safe code restructuring, migrations, and modernization.

Core Capabilities

Safe Renaming

Rename identifiers across the codebase:

Rename workflow:

1. Find all references: Search for all usages
2. Identify scope: Module-local, package-wide, or public API
3. Check dependencies: External code that might break
4. Perform rename: Update all occurrences
5. Verify: Run tests, check imports

Search patterns:

# Find all references to a function
grep -rn "function_name" --include="*.py"

# Find class usages
grep -rn "ClassName" --include="*.py"

# Find imports
grep -rn "from .* import.*function_name" --include="*.py"

Renaming considerations:

• Update docstrings mentioning the old name
• Update comments referencing the name
• Update configuration files
• Update tests
• Consider deprecation period for public APIs

Method Extraction

Extract code into separate functions:

When to extract:

• Code block is too long (> 20 lines)
• Code is duplicated elsewhere
• Code has a clear single purpose
• Code can be tested independently

Extraction process:

1. Identify the code block to extract
2. Determine inputs (parameters)
3. Determine outputs (return values)
4. Create new function with clear name
5. Replace original code with function call
6. Add tests for new function

Before:

def process_order(order):
    # Validate order (candidate for extraction)
    if not order.items:
        raise ValueError("Empty order")
    if order.total < 0:
        raise ValueError("Invalid total")
    for item in order.items:
        if item.quantity <= 0:
            raise ValueError("Invalid quantity")

    # Process payment
    payment_result = gateway.charge(order.total)
    return payment_result

After:

def validate_order(order: Order) -> None:
    """Validate order has valid items and total."""
    if not order.items:
        raise ValueError("Empty order")
    if order.total < 0:
        raise ValueError("Invalid total")
    for item in order.items:
        if item.quantity <= 0:
            raise ValueError("Invalid quantity")

def process_order(order: Order) -> PaymentResult:
    validate_order(order)
    return gateway.charge(order.total)