CODESAMPLE

Chain of Responsibility - C#

Chain of Responsibility C_sharp

The Chain of Responsibility pattern allows a request to be passed along a chain of handlers. Each handler decides either to process the request or to pass it to the next handler in the chain. This decouples the sender of a request from its specific receivers, allowing multiple objects to potentially handle the request without the sender knowing which one.

This C# implementation uses an abstract Handler class defining the chain structure and a HandleRequest method. Concrete handlers (ConcreteHandlerA, ConcreteHandlerB) either process the request if they can, or pass it on. The client creates and links the handlers, then sends the request to the first handler in the chain. C#’s interface and abstract class capabilities are leveraged for flexibility and extensibility, fitting the object-oriented nature of the language.

// Chain of Responsibility
// https://gist.github.com/your-username/your-gist-id

// Abstract Handler
public abstract class Handler
{
    protected Handler _next;

    public void SetNext(Handler next)
    {
        _next = next;
    }

    public abstract void HandleRequest(string request);
}

// Concrete Handlers
public class ConcreteHandlerA : Handler
{
    public override void HandleRequest(string request)
    {
        if (request == "A")
        {
            Console.WriteLine("ConcreteHandlerA handling request: " + request);
        }
        else if (_next != null)
        {
            _next.HandleRequest(request);
        }
        else
        {
            Console.WriteLine("Request not handled.");
        }
    }
}

public class ConcreteHandlerB : Handler
{
    public override void HandleRequest(string request)
    {
        if (request == "B")
        {
            Console.WriteLine("ConcreteHandlerB handling request: " + request);
        }
        else if (_next != null)
        {
            _next.HandleRequest(request);
        }
        else
        {
            Console.WriteLine("Request not handled.");
        }
    }
}

// Client
public class Client
{
    public static void Main(string[] args)
    {
        Handler handlerA = new ConcreteHandlerA();
        Handler handlerB = new ConcreteHandlerB();

        handlerA.SetNext(handlerB);

        handlerA.HandleRequest("A");
        handlerA.HandleRequest("B");
        handlerA.HandleRequest("C");
    }
}