Add mediator examples

src/MediatorPattern/StockExchange/Trader.cs

@@ -0,0 +1,47 @@
+using System;
+
+namespace MediatorPattern.StockExchange
+{
+    /// <summary>
+    /// Colleague
+    /// </summary>
+    public class Trader
+    {
+        public string Name { get; private set; }
+        public Trader(string name, string symbol, int count, double price)
+        {
+            Name = name;
+            Symbol = symbol;
+            Count = count;
+            Price = price;
+        }
+        public string Symbol { get; private set; }
+
+        public int Count { get; private set; }
+
+        public double Price { get; private set; }
+
+        public virtual bool AcceptSell(StockRequest request)
+        {
+            if(request.Price >= Price)
+            {
+                Console.WriteLine("{0} will sell {1} actions of {2} at the price of {3} to {4}",
+                    Name, request.Count, request.Symbol, request.Price, request.Requester);
+                return true;
+            }
+            return false;
+        }
+
+        public virtual bool AcceptBuy(StockRequest request)
+        {
+            if(request.Price <= Price)
+            {
+                Console.WriteLine("{0} will buy {1} actions of {2} at the price of {3} from {4}",
+                    Name, request.Count, request.Symbol, request.Price, request.Requester);
+                return true;
+            }
+
+            return false;
+        }
+    }
+}