using System;

public class Program

{

    public delegate void CallbackType<TReturnType>(bool success, TReturnType returnValue);

    class Foo

    {

        public string Bar; 

    }

​

    static void TestMe(bool successs, Foo foo)

    {

        Console.WriteLine("In TestMe. Foo.Bar incoming as {0}", foo.Bar);

        foo.Bar = "Done";

    }

    static void TestFooCallback(CallbackType<Foo> action)

    {

        var foo = new Foo();

        foo.Bar = "Starting";

        Console.WriteLine(foo.Bar);

​

        action(true, foo);

​

        Console.WriteLine(foo.Bar);

    }

    public static void Main()

    {

        TestFooCallback(TestMe);

    }

}