decorator.md

Decorator Pattern

The Decorator pattern is used to add functionality to an object dynamically. In .NET, the Decorator pattern is implemented using a separate class that wraps the original object and provides additional functionality. This pattern is useful when you want to add functionality to an object without changing its interface.

public interface ICoffee
{
    string GetDescription();
    double GetCost();
}

public class SimpleCoffee : ICoffee
{
    public string GetDescription()
    {
        return "Simple Coffee";
    }

    public double GetCost()
    {
        return 1.0;
    }
}

public class CoffeeWithMilk : ICoffee
{
    private readonly ICoffee _coffee;

    public CoffeeWithMilk(ICoffee coffee)
    {
        _coffee = coffee;
    }

    public string GetDescription()
    {
        return _coffee.GetDescription() + ", with milk";
    }

    public double GetCost()
    {
        return _coffee.GetCost() + 0.5;
    }
}