Fluent interface with extensions in C Sharp (C#) - Mini Project: Build & Apply

Fluent interface with extensions

📖 Scenario: Imagine you are building a simple text formatter for a chat application. You want to create a way to style messages by chaining methods like Bold(), Italic(), and Underline() in a smooth, readable way.

🎯 Goal: Build a fluent interface using extension methods that allows chaining text styling methods on a string. The final output should show the styled text with tags representing the styles.

📋 What You'll Learn

Create a class called TextFormatter that holds a string value.

Create extension methods Bold(), Italic(), and Underline() for TextFormatter.

Each extension method should wrap the current text with corresponding tags: <b>, <i>, and <u> respectively.

Allow chaining of these extension methods to apply multiple styles.

Add a method GetText() to return the final styled string.

💡 Why This Matters

🌍 Real World

Fluent interfaces are common in libraries and frameworks to make code easier to read and write, such as building queries, configuring settings, or styling text.

💼 Career

Understanding fluent interfaces and extension methods is valuable for C# developers, especially when working with APIs like LINQ, Entity Framework, or UI frameworks.

1

Create the TextFormatter class

Create a public class called TextFormatter with a public string property called Text. Add a constructor that takes a string parameter called text and sets the Text property.

C Sharp (C#)

public class TextFormatter
{
    // Your code here
}

Need a hint?

Remember to create a constructor that sets the Text property from the parameter.

2

Add the Bold extension method

Create a public static class called TextFormatterExtensions. Inside it, create a public static method called Bold that takes a TextFormatter parameter named formatter with the this keyword. The method should wrap formatter.Text with <b> and </b> tags, update formatter.Text, and return the formatter object.

C Sharp (C#)

public class TextFormatter
{
    public string Text { get; set; }

    public TextFormatter(string text)
    {
        Text = text;
    }
}

// Your code here

Need a hint?

Use this TextFormatter formatter as the first parameter to make it an extension method.

3

Add Italic and Underline extension methods

Inside the TextFormatterExtensions class, add two more public static extension methods: Italic and Underline. Both take a TextFormatter parameter named formatter with this. Italic should wrap formatter.Text with <i> and </i>. Underline should wrap formatter.Text with <u> and </u>. Both methods update formatter.Text and return formatter.

C Sharp (C#)

public class TextFormatter
{
    public string Text { get; set; }

    public TextFormatter(string text)
    {
        Text = text;
    }
}

public static class TextFormatterExtensions
{
    public static TextFormatter Bold(this TextFormatter formatter)
    {
        formatter.Text = $"{formatter.Text}";
        return formatter;
    }

    // Your code here
}

Need a hint?

Follow the same pattern as Bold for both Italic and Underline.

4

Use the fluent interface and print the result

In the Main method, create a new TextFormatter object with the text "Hello". Chain the extension methods Bold(), Italic(), and Underline() in that order. Then print the final Text property of the object using Console.WriteLine.

C Sharp (C#)

public class TextFormatter
{
    public string Text { get; set; }

    public TextFormatter(string text)
    {
        Text = text;
    }
}

public static class TextFormatterExtensions
{
    public static TextFormatter Bold(this TextFormatter formatter)
    {
        formatter.Text = $"{formatter.Text}";
        return formatter;
    }

    public static TextFormatter Italic(this TextFormatter formatter)
    {
        formatter.Text = $"{formatter.Text}";
        return formatter;
    }

    public static TextFormatter Underline(this TextFormatter formatter)
    {
        formatter.Text = $"{formatter.Text}";
        return formatter;
    }
}

class Program
{
    static void Main()
    {
        // Create a TextFormatter with "Hello" and chain Bold, Italic, Underline
        // Then print the final Text
        // Your code here
    }
}

Need a hint?

Remember to create the TextFormatter object first, then chain the extension methods, and finally print the Text property.