FirstRxExample.RxStockMonitor.RxStockMonitor C# (CSharp) Method

        public RxStockMonitor(IStockTicker ticker)
        {
            const decimal maxChangeRatio = 0.1m;

            //creating an observable from the StockTick event, each notification will carry only the eventargs and will be synchronized
            IObservable<StockTick> ticks =
                    Observable.FromEventPattern<EventHandler<StockTick>, StockTick>(
                        h => ticker.StockTick += h,
                        h => ticker.StockTick -= h)
                        .Select(tickEvent => tickEvent.EventArgs)
                        .Synchronize();

            var drasticChanges =
                from tick in ticks
                group tick by tick.QuoteSymbol
                into company
                from tickPair in company.Buffer(2, 1)
                let changeRatio = Math.Abs((tickPair[1].Price - tickPair[0].Price) / tickPair[0].Price)
                where changeRatio > maxChangeRatio
                select new DrasticChange()
                {
                    Symbol = company.Key,
                    ChangeRatio = changeRatio,
                    OldPrice = tickPair[0].Price,
                    NewPrice = tickPair[1].Price
                };

            DrasticChanges = drasticChanges;

            _subscription =
                drasticChanges.Subscribe(change =>
                    {
                        Console.WriteLine("Stock:{0} has changed with {1} ratio, Old Price:{2} New Price:{3}", change.Symbol,
                            change.ChangeRatio,
                            change.OldPrice,
                            change.NewPrice);
                    },
                    ex => { /* code that handles erros */}, //#C
                    () => {/* code that handles the observable completenss */}); //#C
        }