C# 5.0 async wrapper for WCF services.

gistfile1.cs

    public class WcfAsyncWrapper<TEventArgs, TResult> where TEventArgs : AsyncCompletedEventArgs
    { 
        private readonly bool _haveResult;
        private readonly TaskCompletionSource<TResult> _taskCompletionSource;
        private EventHandler<TEventArgs> _event;

        public WcfAsyncWrapper(bool haveResult = true)
        {
            _haveResult = haveResult;
            _taskCompletionSource = new TaskCompletionSource<TResult>();
        }

        public EventHandler<TEventArgs> Event
        {
            get
            {
                if (_event != null)
                    return _event;

                return _event = GenericAsyncEvent;

            }
        }

        private void GenericAsyncEvent(object sender, TEventArgs args)
        {
            if (args.Cancelled)
                _taskCompletionSource.SetCanceled();
            else if (args.Error != null)
                _taskCompletionSource.SetException(args.Error);

            ///
            /// Retrieve the Result
            /// 

            TResult result = default(TResult);

            if (_haveResult)
            {
                var property = args.GetType().GetProperty("Result");
                result = (TResult) property.GetValue(args, null);
                
            }
            _taskCompletionSource.SetResult(result);
        }

        public Task<TResult> Task
        {
            get { return _taskCompletionSource.Task; }
        }

        public static WcfAsyncWrapper<TArgs,object> FromVoidResult<TArgs>() where TArgs : AsyncCompletedEventArgs
        {
            return new WcfAsyncWrapper<TArgs, object>(false);
        }
    }

///
///    USAGE
///
var wcfAsyncWrapper = new WcfAsyncWrapper<GetDataFromRawInformationCompletedEventArgs, MediaInfoResult>();
Client.GetDataFromRawInformationCompleted += wcfAsyncWrapper.Event; 
Client.GetDataFromRawInformationAsync(data);
var result = await wcfAsyncWrapper.Task;