using System;

using System.Threading.Tasks;

​

namespace Example

{

    public class Program

    {

        static public void Main()

        {

            var library = new Library();

            library.Callback = GetMoreData;

            var task = Task.Run( () => library.Foo() );

            Console.WriteLine("Other thread is running.");

            task.Wait();

        }

​

        static string GetMoreData()

        {

            return "More data";

        }

    }

​

​

​

    class Library

    {

        public Func<string> Callback { get; set; }

​

        public async Task Foo()

        {

            for (int i=0; i<10; i++)

            {

                var moreData = Callback();

                Console.WriteLine("Library received this data: {0}", moreData);

                await Task.Delay(500);

            }

        }

    }    

​

​

​

​

}