refactor-planner

Refactor Planner

Plan safe, incremental refactoring with proper impact analysis.

Refactoring Workflow

1. Analyze → 2. Plan → 3. Test → 4. Execute → 5. Verify

1. Analyze Current State

• Understand existing code structure
• Map dependencies (what uses this code)
• Identify coupling and cohesion issues
• Document current behavior with tests

2. Plan the Refactoring

• Define target state clearly
• Break into small, reversible steps
• Identify risk points
• Plan rollback strategy

3. Test Coverage First

• Ensure existing tests pass
• Add tests for uncovered behavior
• Create integration tests for dependencies
• Never refactor without tests

4. Execute Incrementally

• One logical change per commit
• Run tests after each step
• Keep the system working throughout
• Commit frequently

5. Verify Results

• All tests still pass
• No new warnings/errors
• Performance unchanged (or improved)
• Dependencies still work

Refactoring Patterns

Extract Function

When: Code block is reused or too complex

# Before
def process_order(order):
    # Calculate total
    total = 0
    for item in order.items:
        price = item.price * item.quantity
        if item.discount:
            price *= (1 - item.discount)
        total += price
    # ... more code

# After
def calculate_item_price(item) -> float:
    """Calculate price for single item with discount."""
    price = item.price * item.quantity
    if item.discount:
        price *= (1 - item.discount)
    return price

def calculate_order_total(order) -> float:
    """Calculate total order price."""
    return sum(calculate_item_price(item) for item in order.items)

def process_order(order):
    total = calculate_order_total(order)
    # ... more code

Extract Class

When: A class has too many responsibilities

# Before: User class doing too much
class User:
    def authenticate(self, password): ...
    def send_email(self, subject, body): ...
    def generate_report(self): ...

# After: Split by responsibility
class User:
    def __init__(self):
        self.auth = UserAuthenticator(self)
        self.notifier = UserNotifier(self)
        self.reporter = UserReporter(self)

class UserAuthenticator:
    def authenticate(self, password): ...

class UserNotifier:
    def send_email(self, subject, body): ...

class UserReporter:
    def generate_report(self): ...