Refactoring Code in C++ for Enhanced Clarity and Efficiency

Introduction

Hello, explorer! Today is about refactoring . Think of it as organizing your favorite tool chest. We're going to learn about Extract Method, Rename Method, and Substitute Algorithm refactorings in C++. Refactoring helps us tidy up our code, making it cleaner and more maintainable, all while preserving its functionality.

Refactoring Overview

Consider having a complicated blueprint. Refactoring changes it into a clearer drawing. Our code is rearranged to enhance readability and efficiency without altering its behavior. Let's examine a short code snippet before and after refactoring: C++ // Before refactoring double calculate(double total, int quantity) {double price = total / quantity; double tax = price * 0.2; double totalPrice = price + tax; return totalPrice;} // Before refactoring double calculate(double total, int quantity) {double price = total / quantity; double tax = price * 0.2; double totalPrice = price + tax; return totalPrice;} C++ // After refactoring double calculatePrice(double total, int quantity) {return total / quantity;} double calculateTax(double price) {return price * 0.2;} double calculateTotalPrice(double total, int quantity) {double price = calculatePrice(total, quantity); double tax = calculateTax(price); return price + tax;} // After refactoring double calculatePrice(double total, int quantity) {return total / quantity;} double calculateTax(double price) {return price * 0.2;} double calculateTotalPrice(double total, int quantity) {double price = calculatePrice(total, quantity); double tax = calculateTax(price); return price + tax;} Both code versions perform the same function, but the refactored version is simpler and easier to comprehend!

Understanding the Extract Method

Imagine a large set of instructions for setting up a desktop. The Extract Method technique is like having separate instructions for the monitor, CPU, keyboard, etc., instead of one large set of instructions. Observe this code: C++// Before refactoring std::string greetUser(std::string username) { // Prepare the username std::transform(username.begin(), username.end(), username.begin(), ::tolower); username.erase(username.find_last_not_of(" \n\r\t")+1); // Find the last non-whitespace character and erase everything after it std::string message = "Hello, " + username + "!"; // Prepare the message return message; // Return the prepared message }// Before refactoring std::string greetUser(std::string username) { // Prepare the username std::transform(username.begin(), username.end(), username.begin(), ::tolower); username.erase(username.find_last_not_of(" \n\r\t")+1); // Find the last non-whitespace character and erase everything after it std::string message = "Hello, " + username + "!"; // Prepare the message return message; // Return the prepared message } C++// After refactoring std::string cleanUsername(std::string username) { // Returns a cleaned version of the username std::transform(username.begin(), username.end(), username.begin(), ::tolower); username.erase(username.find_last_not_of(" \n\r\t")+1); // Find the last non-whitespace character and erase everything after it return username; } std::string greetUser(std::string username) { username = cleanUsername(username); // Clean the username std::string message = "Hello, " + username + "!"; // Prepare and return the message return message; }// After refactoring std::string cleanUsername(std::string username) { // Returns a cleaned version of the username std::transform(username.begin(), username.end(), username.begin(), ::tolower); username.erase(username.find_last_not_of(" \n\r\t")+1); // Find the last non-whitespace character and erase everything after it return username; } std::string greetUser(std::string username) { username = cleanUsername(username); // Clean the username std::string message = "Hello, " + username + "!"; // Prepare and return the message return message; } Here, we moved the username preparation from greetUser into its dedicated function cleanUsername. Neat and organized!

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C++

// Before refactoring
double calculate(double total, int quantity) {
    double price = total / quantity;
    double tax = price * 0.2;
    double totalPrice = price + tax;
    return totalPrice;
}

C++

// After refactoring
double calculatePrice(double total, int quantity) {
    return total / quantity;
}

double calculateTax(double price) {
    return price * 0.2;
}

double calculateTotalPrice(double total, int quantity) {
    double price = calculatePrice(total, quantity);
    double tax = calculateTax(price);
    return price + tax;
}

C++

// Before refactoring
std::string greetUser(std::string username) {
    // Prepare the username
    std::transform(username.begin(), username.end(), username.begin(), ::tolower);
    username.erase(username.find_last_not_of(" \n\r\t")+1); // Find the last non-whitespace character and erase everything after it
    std::string message = "Hello, " + username + "!"; // Prepare the message
    return message; // Return the prepared message
}

C++

// After refactoring
std::string cleanUsername(std::string username) {
    // Returns a cleaned version of the username
    std::transform(username.begin(), username.end(), username.begin(), ::tolower);
    username.erase(username.find_last_not_of(" \n\r\t")+1); // Find the last non-whitespace character and erase everything after it
    return username;
}

std::string greetUser(std::string username) {
    username = cleanUsername(username); // Clean the username
    std::string message = "Hello, " + username + "!"; // Prepare and return the message
    return message;
}

C++

// Before refactoring
double fx(double x) {
    return 3.14 * x * x; // Calculates a value that is pi times the square of x
}

// Before refactoring
double fx(double x) {
    return 3.14 * x * x; // Calculates a value that is pi times the square of x
}

C++

// After refactoring
double calculateCircleArea(double radius) {
    return 3.14 * radius * radius; // Calculates the area of a circle with a given radius
}

// After refactoring
double calculateCircleArea(double radius) {
    return 3.14 * radius * radius; // Calculates the area of a circle with a given radius
}

C++

// Before refactoring
int findSmallest(const std::vector<int>& numbers) {
    int smallest = numbers[0];
    for (int num : numbers) {
        if (num < smallest) { 
            smallest = num;
        }
    }
    return smallest;
}

// Before refactoring
int findSmallest(const std::vector<int>& numbers) {
    int smallest = numbers[0];
    for (int num : numbers) {
        if (num < smallest) { 
            smallest = num;
        }
    }
    return smallest;
}

C++

// After refactoring
int findSmallest(const std::vector<int>& numbers) {
    return *std::min_element(numbers.begin(), numbers.end()); // Returns the smallest number from 'numbers'
}

// After refactoring
int findSmallest(const std::vector<int>& numbers) {
    return *std::min_element(numbers.begin(), numbers.end()); // Returns the smallest number from 'numbers'
}

C++

// Before refactoring
double fx(double x) {
    return 3.14 * x * x; // Calculates a value that is pi times the square of x
}

C++

// After refactoring
double calculateCircleArea(double radius) {
    return 3.14 * radius * radius; // Calculates the area of a circle with a given radius
}

C++

// Before refactoring
int findSmallest(const std::vector<int>& numbers) {
    int smallest = numbers[0];
    for (int num : numbers) {
        if (num < smallest) { 
            smallest = num;
        }
    }
    return smallest;
}

C++

// After refactoring
int findSmallest(const std::vector<int>& numbers) {
    return *std::min_element(numbers.begin(), numbers.end()); // Returns the smallest number from 'numbers'
}

Introduction

Refactoring Overview

Understanding the Extract Method

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Using Rename Method

Discovering Substitute Algorithm

Lesson Summary and Practice