Future

Future

using System;

namespace Squisqula
{
    public class Future<T>
    {
        public bool IsCompleted { get { return _isCompleted; } }

        public T Result
        {
            get
            {
                if (!_isCompleted)
                    throw new InvalidOperationException("Future is not completed.");

                return _result;
            }
        }

        public event EventHandler Completed;

        protected void SetResult(T result)
        {
            _result = result;
            _isCompleted = true;
            var handler = Completed;
            if (handler != null)
            {
                handler(this, EventArgs.Empty);
            }
        }

        private bool _isCompleted;
        private T _result;
    }

    public sealed class Promise<T>
    {
        private class FutureImpl<U> : Future<U>
        {
            internal new void SetResult(U result)
            {
                base.SetResult(result);
            }
        }

        public Future<T> Future { get { return _future; } }

        public void SetResult(T result)
        {
            _future.SetResult(result);
        }

        private readonly FutureImpl<T> _future = new FutureImpl<T>();
    }
}