Refactoring Techniques in C#

Lesson 2

Introduction

Hello, Explorer! Today is about refactoring. Consider it as organizing your favorite toys in the toybox. We're going to learn about the Extract Method, Rename Method, and Substitute Algorithm refactorings. Refactoring helps us make our code cleaner and neater while keeping the functionality the same!

Refactoring Overview

Imagine having a complex map. Refactoring transforms it into simpler directions. Our code gets rearranged to make it more readable and efficient without altering what it does. Let's consider a small code snippet before and after refactoring:

C#
1// Before refactoring
2public double Calculate(double total, int quantity) {
3    double price = total / quantity;
4    double tax = price * 0.2;
5    double totalPrice = price + tax;
6    return totalPrice;
7}
8
9// After refactoring
10public double CalculateTotalPrice(double total, int quantity) {
11    double price = CalculatePrice(total, quantity);
12    double tax = CalculateTax(price);
13    return price + tax;
14}
15
16public double CalculatePrice(double total, int quantity) {
17    return total / quantity;
18}
19
20public double CalculateTax(double price) {
21    return price * 0.2;
22}

Both versions of the code do the same thing, but the latter is simpler and easier to understand!

Understanding the Extract Method

Imagine a large recipe for a complete breakfast. The Extract Method technique is like having separate recipes for eggs, toast, coffee, etc., instead of one large recipe. Take a look at this code:

C#
1// Before refactoring
2public string GreetUser(string username) {
3    username = username.Trim().ToLowerInvariant(); // Prepare the username
4    string message = "Hello, " + username + "!"; // Prepare the message
5    return message; // Return the prepared message
6}
7
8// After refactoring
9public string CleanUsername(string username) {
10    return username.Trim().ToLowerInvariant(); // Returns a cleaned version of the username
11}
12
13public string GreetUser(string username) {
14    username = CleanUsername(username); // Clean the username
15    string message = "Hello, " + username + "!"; // Prepare and return the message
16    return message;
17}

Here, we moved the username preparation from GreetUser into its own function, CleanUsername. Nice and tidy!

Using Rename Method

Clear method names make it easy to understand our code, just as clear street names make navigating a city more accessible. Let's have a look at renaming a method:

C#
1// Before refactoring
2public double Fx(double x) {
3    return 3.14 * (x * x); // Calculates a value that is pi times the square of x
4}
5
6// After refactoring
7public double CalculateCircleArea(double radius) {
8    return 3.14 * (radius * radius); // Calculates the area of a circle with a given radius
9}

Renaming the function Fx to CalculateCircleArea makes it easier to understand its purpose.

Discovering Substitute Algorithm

A Substitute Algorithm involves replacing a part of a code (an algorithm) with a simpler one, analogous to discovering a faster route to school. Here's an example:

C#
1// Before refactoring
2public int FindSmallest(int[] numbers) {
3    int smallest = int.MaxValue;
4    foreach (var num in numbers) {
5        if (num < smallest) {
6            smallest = num;
7        }
8    }
9    return smallest;
10}
11
12// After refactoring
13using System.Linq;
14
15public int FindSmallest(int[] numbers) {
16    return numbers.Min(); // Returns the smallest number from 'numbers'
17}

Using numbers.Min() from LINQ performs the same job as our previous function but with less code.

Lesson Summary

Great work! We've learned how to use the Extract Method, Rename Method, and Substitute Algorithm to keep our code clean and efficient. Now, it's time for some hands-on practice with real examples. Remember, practice makes perfect. Let's do some refactoring!

Enjoy this lesson? Now it's time to practice with Cosmo!

Practice is how you turn knowledge into actual skills.