Add RX variance to Stocks example on Observer pattern

src/BehavioralPatterns/Program.cs

@@ -15,6 +15,8 @@ namespace BehavioralPatterns
     {
         public static void Main(string[] args)
         {
+            ObserverPatternExamples.Run();
+            Console.ReadKey();
             //Chain of responsibillity
             //This is usefull when you have a request and you don't know who should process it
             ChainOfResponsibillityExamples.Run();
@@ -40,8 +42,6 @@ namespace BehavioralPatterns
 
             Console.ReadKey();
 
-            ObserverPatternExamples.Run();
-            Console.ReadKey();
 
         }
     }

src/ObserverPattern/ObserverPatternExamples.cs

@@ -19,12 +19,22 @@ namespace ObserverPattern
             StockUpdateEventsExample stockExample = new StockUpdateEventsExample();
             stockExample.RunSimple();
 
-            GoToNextStep();
+            GoToNextStep();            
-            Console.WriteLine("Same business logic using RX");
-            stockExample.RunReactive();
 
             Console.WriteLine(GetLapsedLinstenerProblem());
 
+            GoToNextStep();
+
+            Console.WriteLine("Same business logic using events combined with RX library");
+            stockExample.RunReactiveWithEvents();
+
+            GoToNextStep();
+
+            Console.WriteLine("Same business logic using RX library");
+            stockExample.RunReactive();
+
+            GoToNextStep();
+
             ObservableTwitsExample obsTwits = new ObservableTwitsExample();
             obsTwits.Run();
 

src/ObserverPattern/StockUpdateEvents/StockSubject.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Reactive.Subjects;
 
 namespace ObserverPattern.StockUpdateEvents
 {
@@ -7,12 +8,12 @@ namespace ObserverPattern.StockUpdateEvents
     /// </summary>
     public class StockSubject
     {
-
         public void UpdateStockValue(Stock s)
         {
             StockUpdated?.Invoke(this, new StockUpdateEventArgs(s));
         }
 
         public event EventHandler<StockUpdateEventArgs> StockUpdated;
+        
     }
 }

src/ObserverPattern/StockUpdateEvents/StockUpdateEventsExample.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reactive;
 using System.Reactive.Linq;
+using System.Reactive.Subjects;
 using System.Threading.Tasks;
 
 namespace ObserverPattern.StockUpdateEvents
@@ -20,7 +21,7 @@ namespace ObserverPattern.StockUpdateEvents
             PublishUpdateStocks(stockSubject);
         }        
 
-        public void RunReactive()
+        public void RunReactiveWithEvents()
         {
             StockSubject stockSubject = new StockSubject();
 
@@ -39,14 +40,38 @@ namespace ObserverPattern.StockUpdateEvents
             }
         }
 
+        public void RunReactive()
+        {
+            Subject<Stock> stockSubject = new Subject<Stock>();
+
+            var londonObserver = stockSubject.Where(s => s.Name == "FTSE");
+            var aaplObserver = stockSubject.Where(s => s.Name == "AAPL");
+
+            using (londonObserver.Subscribe(PrintLondonStockPriceUpdate))
+            using (aaplObserver.Subscribe(PrintAaplStockPriceUpdate))
+            {
+                PublishUpdateStocks(stockSubject);
+            }
+        }
+
         private void PrintAaplStockPriceUpdate(EventPattern<StockUpdateEventArgs> eventP)
         {
-            Console.WriteLine("apple updated, new value: {0}", eventP.EventArgs.Stock.Value);
+            PrintAaplStockPriceUpdate(eventP.EventArgs.Stock);
+        }
+
+        private void PrintAaplStockPriceUpdate(Stock stock)
+        {
+            Console.WriteLine("apple updated, new value: {0}", stock.Value);
         }
 
         private void PrintLondonStockPriceUpdate(EventPattern<StockUpdateEventArgs> eventP)
         {
-            Console.WriteLine("london stock updated, new value: {0}", eventP.EventArgs.Stock.Value);
+            PrintLondonStockPriceUpdate(eventP.EventArgs.Stock);
+        }
+
+        private void PrintLondonStockPriceUpdate(Stock stock)
+        {
+            Console.WriteLine("london stock updated, new value: {0}", stock.Value);
         }
 
         private static void PublishUpdateStocks(StockSubject stockSubject)
@@ -61,5 +86,18 @@ namespace ObserverPattern.StockUpdateEvents
             stockSubject.UpdateStockValue(new Stock { Name = "FTSE", Value = 2 });
             stockSubject.UpdateStockValue(new Stock { Name = "FTSE", Value = 3 });
         }
+
+        private static void PublishUpdateStocks(Subject<Stock> stockSubject)
+        {
+            stockSubject.OnNext(new Stock { Name = "AAPL", Value = 3 });
+            stockSubject.OnNext(new Stock { Name = "AAPL", Value = 4 });
+            stockSubject.OnNext(new Stock { Name = "AAPL", Value = 5 });
+            stockSubject.OnNext(new Stock { Name = "AAPL", Value = 6 });
+
+            stockSubject.OnNext(new Stock { Name = "FTSE", Value = 6 });
+            stockSubject.OnNext(new Stock { Name = "FTSE", Value = 12 });
+            stockSubject.OnNext(new Stock { Name = "FTSE", Value = 2 });
+            stockSubject.OnNext(new Stock { Name = "FTSE", Value = 3 });
+        }
     }
 }