Create ItemListT.cs

Author: RexJaeschke

tools/example-templates/additional-files/ItemListT.cs

@@ -0,0 +1,22 @@
+class ItemList<T> : List<T>
+{
+    public int Sum(Func<T, int> selector)
+    {
+        int sum = 0;
+        foreach (T item in this)
+        {
+            sum += selector(item);
+        }
+        return sum;
+    }
+
+    public double Sum(Func<T, double> selector)
+    {
+        double sum = 0;
+        foreach (T item in this)
+        {
+            sum += selector(item);
+        }
+        return sum;
+    }
+}