Structural Patterns - Decorator C# demo

Decorator.cs

using System;

class MainApp
{
    static void Main()
    {
        // Create ConcreteComponent and two Decorators 
        ConcreteComponent c = new ConcreteComponent();
        ConcreteDecoratorA d1 = new ConcreteDecoratorA();
        ConcreteDecoratorB d2 = new ConcreteDecoratorB();

        // Link decorators 
        d1.SetComponent(c);
        d2.SetComponent(d1);

        d2.Operation();

        // Wait for user 
        Console.Read();
    }
}

// "Component" 
abstract class Component
{
    public abstract void Operation();
}

// "ConcreteComponent" 
class ConcreteComponent : Component
{
    public override void Operation()
    {
        Console.WriteLine("ConcreteComponent.Operation()");
    }
}

// "Decorator" 
abstract class Decorator : Component
{
    protected Component component;

    public void SetComponent(Component component)
    {
        this.component = component;
    }

    public override void Operation()
    {
        if (component != null)
        {
            component.Operation();
        }
    }
}

// "ConcreteDecoratorA" 
class ConcreteDecoratorA : Decorator
{
    private string addedState;

    public override void Operation()
    {
        base.Operation();
        addedState = "New State";
        Console.WriteLine("ConcreteDecoratorA.Operation()");
    }
}

// "ConcreteDecoratorB" 
class ConcreteDecoratorB : Decorator
{
    public override void Operation()
    {
        base.Operation();
        AddedBehavior();
        Console.WriteLine("ConcreteDecoratorB.Operation()");
    }

    void AddedBehavior()
    {
    }
}