Passing requesting class type to a requested class constructor

Question

Let's say I have a following class:

public class Handler
{
    public Type RequesterType { get; }

    public Handler(Type requesterType)
    {
        RequesterType = requesterType;
    }
}

which is itself a dependency of another class:

public class Controller
{
    public Handler Handler { get; }

    public Controller(Handler handler)
    {
        Handler = handler;
    }
}

---

Is it possible to register Handler in such a way that when Controller is being resolved, the dependent Handler 's constructor argument requesterType is being assigned with Controller type?

Here's an example of what I want to achieve:

class Program
{
    static void Main(string[] args)
    {
        var container = new WindsorContainer();
        container.Register(
            Component.For<Controller>()
            //Component.For<Handler>(), <- this is the essense of my question
        );

        var controller = container.Resolve<Controller>();
        Console.WriteLine(controller.Handler.RequesterType); //Should output Program.Controller
        Console.ReadKey();
    }
}

Answer 1

A common way to handle this would be to make Handler generic:

public class Handler<T>
{
    public Type RequesterType { get { return typeof(T) ; }
}

Then instead of passing the type in the constructor, you'd pass it as a generic type parameter:

public class Controller
{
    public Handler<Controller> Handler { get; }

    public Controller(Handler<Controller> handler)
    {
        Handler = handler;
    }
}

Now you can register your handlers per controller in the usual way, and they will resolve for the right type.

You may want to embellish this a bit with interfaces or covariance, but that is the general idea.