C# 14 - Extension Method features

In C# 14, extension methods are enhanced with a new feature called Extension Members.
You can now extend a type with methods, properties, operators, and static members using the new extension block syntax.

Below is a clear example using public static class PersonExtensions.

Person Class (Original Class)

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }

    public Person(string firstName, string lastName, int age)
    {
        FirstName = firstName;
        LastName = lastName;
        Age = age;
    }
}

Extension Members Class

public static class PersonExtensions
{
    // Extension members for Person instance
    extension(Person p)
    {
        // Extension Property
        public string FullName => $"{p.FirstName} {p.LastName}";

        // Extension Method
        public bool IsAdult()
        {
            return p.Age >= 18;
        }

        // Extension Method
        public string GetDetails()
        {
            return $"{p.FirstName} {p.LastName} is {p.Age} years old";
        }
    }

    // Extension Static Member
    extension(Person)
    {
        public static string Species => "Homo Sapiens";
    }
}

Program Usage

using System;

class Program
{
    static void Main()
    {
        Person p1 = new Person("John", "Doe", 25);

        // Extension Property
        Console.WriteLine(p1.FullName);

        // Extension Method
        Console.WriteLine(p1.IsAdult());

        // Extension Method
        Console.WriteLine(p1.GetDetails());

        // Extension Static Member
        Console.WriteLine(Person.Species);
    }
}

Output

John Doe
True
John Doe is 25 years old
Homo Sapiens

Conclusion

C# 14 introduces Extension Members, which allow developers to add methods, properties, operators, and static members to existing types using the extension(Type) syntax.