Cursor Code Refactoring: 5 Steps to Improve Code Maintainability

Introduction

As a developer, do you often encounter the frustration of increasingly messy project code, functions that easily exceed hundreds of lines, unclear class responsibilities, and changes that could trigger a chain reaction? These are typical manifestations of poor code maintainability. The traditional refactoring process requires developers to manually analyze code structure, extract methods, and optimize designs, which is not only time-consuming but also prone to errors.

Cursor, as a new generation AI programming assistant, can intelligently identify code smells, automatically provide refactoring suggestions, and execute refactoring operations with a single click. This tutorial will show you how to use Cursor to quickly improve code maintainability in 5 steps, making the code clearer, easier to understand, and easier to modify.

1. Extract Duplicate Code into Independent Functions

Concept Introduction

Duplicate code is one of the most common code smells. Cursor can automatically identify duplicate code snippets and extract them into independent functions.

Steps

1. Select the area containing duplicate code 2. Press Command+Shift+P (Mac) or Ctrl+Shift+P (Windows) 3. Type “Extract Method” 4. Enter the new function name

Code Example

# Before Refactoring
def process_user_data(user):
    # Validate user information
    if not user.name or len(user.name) < 2:
        raise ValueError("Invalid name")
    if not user.email or '@' not in user.email:
        raise ValueError("Invalid email")

# Process user data
user.name = user.name.strip()
user.email = user.email.lower()

def process_admin_data(admin):
    # Validate admin information
    if not admin.name or len(admin.name) < 2:
        raise ValueError("Invalid name")
    if not admin.email or '@' not in admin.email:
        raise ValueError("Invalid email")

# Process admin data
admin.name = admin.name.strip()
admin.email = admin.email.lower()

# After Refactoring
def validate_person(person):
    if not person.name or len(person.name) < 2:
        raise ValueError("Invalid name")
    if not person.email or '@' not in person.email:
        raise ValueError("Invalid email")

def process_data(person):
    person.name = person.name.strip()
    person.email = person.email.lower()

def process_user_data(user):
    validate_person(user)
    process_data(user)

def process_admin_data(admin):
    validate_person(admin)
    process_data(admin)

💡 Tip: The extracted function name should clearly express its functionality rather than being overly abstract.

2. Simplify Complex Conditional Logic

Concept Introduction

Complex conditional statements can reduce the readability of code. Cursor can help us extract complex conditions into independent functions or introduce explanatory variables.

Code Example

# Before Refactoring
def calculate_discount(order):
    if (order.total_amount > 1000 and order.user.vip_level > 2 and
        order.create_time.month == 12 and not order.is_promotion):
        return 0.2
    return 0

# After Refactoring
def is_christmas_season(date):
    return date.month == 12

def is_eligible_for_vip_discount(user):
    return user.vip_level > 2

def is_big_order(amount):
    return amount > 1000

def calculate_discount(order):
    is_special_discount = (
        is_big_order(order.total_amount) and
        is_eligible_for_vip_discount(order.user) and
        is_christmas_season(order.create_time) and
        not order.is_promotion
    )
    return 0.2 if is_special_discount else 0

⚠️ Note: The extracted condition functions should return a boolean value, and function names typically start with is_, has_, should_, etc.

3. Split Long Functions

Concept Introduction

Long functions usually indicate that they are doing too much. Using Cursor can quickly identify the boundaries of a function’s responsibilities and split them.

Code Example

# Before Refactoring
def process_order(order):
    # Validate order
    if not order.items:
        raise ValueError("Empty order")
    if not order.user:
        raise ValueError("No user")

# Calculate total price
total = 0
for item in order.items:
    if item.quantity <= 0:
        raise ValueError("Invalid quantity")
    total += item.price * item.quantity

# Apply discount
if order.user.vip_level > 2:
    total = total * 0.9

# Update inventory
for item in order.items:
    item.product.stock -= item.quantity
    if item.product.stock < 0:
        raise ValueError("Out of stock")

return total

# After Refactoring
def validate_order(order):
    if not order.items:
        raise ValueError("Empty order")
    if not order.user:
        raise ValueError("No user")
    for item in order.items:
        if item.quantity <= 0:
            raise ValueError("Invalid quantity")

def calculate_total(items):
    return sum(item.price * item.quantity for item in items)

def apply_vip_discount(total, user):
    return total * 0.9 if user.vip_level > 2 else total

def update_inventory(items):
    for item in items:
        item.product.stock -= item.quantity
        if item.product.stock < 0:
            raise ValueError("Out of stock")

def process_order(order):
    validate_order(order)
    total = calculate_total(order.items)
    total = apply_vip_discount(total, order.user)
    update_inventory(order.items)
    return total

📌 Key Points: Each function after splitting should only do one thing, making it easier to test and maintain.

4. Introduce Design Patterns

Concept Introduction

Appropriate design patterns can make the code structure clearer. Cursor can identify scenarios in the code suitable for applying design patterns.

Code Example

# Before Refactoring
class OrderProcessor:
    def process(self, order):
        if order.type == "online":
            # Process online order
            pass
        elif order.type == "offline":
            # Process offline order
            pass
        elif order.type == "wholesale":
            # Process wholesale order
            pass

# After Refactoring (Strategy Pattern)
class OrderStrategy:
    def process(self, order):
        pass

class OnlineOrderStrategy(OrderStrategy):
    def process(self, order):
        # Process online order
        pass

class OfflineOrderStrategy(OrderStrategy):
    def process(self, order):
        # Process offline order
        pass

class WholesaleOrderStrategy(OrderStrategy):
    def process(self, order):
        # Process wholesale order
        pass

class OrderProcessor:
    def __init__(self):
        self.strategies = {
            "online": OnlineOrderStrategy(),
            "offline": OfflineOrderStrategy(),
            "wholesale": WholesaleOrderStrategy()
        }

    def process(self, order):
        strategy = self.strategies.get(order.type)
        if not strategy:
            raise ValueError("Invalid order type")
        return strategy.process(order)

Conclusion

Key Points:

1. Identifying and eliminating code duplication is the first step in refactoring. 2. Simplifying complex logic through function extraction and introducing explanatory variables. 3. Reasonably using design patterns can improve the extensibility of the code.

Practice Suggestions:

1. Find a long function in an existing project and try using Cursor to split it. 2. Use Cursor’s refactoring suggestion feature to analyze code smells in the project. 3. Practice refactoring if-else branching using the strategy pattern.

Remember, code refactoring is a continuous process. It is recommended to cultivate the awareness of refactoring in daily development and address code smells promptly. Start small and gradually build a good code structure.

💡 Tip: Ensure sufficient test coverage before refactoring to guarantee that refactoring does not introduce new issues.