using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Threading;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Future<string> f = new Future<string>(Foo);
            ThreadPool.QueueUserWorkItem(x => { Thread.Sleep(3 * 1000); f.Excute(); });
            //ThreadPool.QueueUserWorkItem(x => f.Excute());

Thread.Sleep(1000);
            Console.WriteLine("waitting answer...");

//f.Wait();
            //Console.WriteLine("answer:\t" + f.Value);

if (f.Wait(TimeSpan.FromSeconds(5)))
                Console.WriteLine("answer:\t" + f.Value);
            else
                Console.WriteLine("time out");

Console.WriteLine("test finished");
            Thread.Sleep(-1);
        }

static string Foo()
        {
            Console.WriteLine("foo begin");
            string s = Console.ReadLine();
            Console.WriteLine("foo finished.");
            return s;
        }
    }

delegate T ExcuteHanlder<T>();

class Future<T>
    {
        public T Value { get; private set; }
        public bool Ready { get; private set; }

ExcuteHanlder<T> function;
        public Future(ExcuteHanlder<T> function)
        {
            this.function = function;
        }

public void Excute()
        {
            Value = function();

lock (this)
            {
                Ready = true;
                Monitor.Pulse(this);
            }
        }

public bool Wait()
        {
            return Wait(TimeSpan.Zero);
        }

public bool Wait(TimeSpan timeout)
        {
            lock (this)
            {

if (!Ready)
                {
                    if (timeout == TimeSpan.Zero)
                        return Monitor.Wait(this);
                    else
                        return Monitor.Wait(this, timeout);
                }
            }
            return true;
        }

}
}