diff -r acf2c31e22d4 -r 40cabcdcd2be samples/composition/src-api2.0-enum/org/apidesign/math/Arithmetica.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/composition/src-api2.0-enum/org/apidesign/math/Arithmetica.java	Thu Oct 30 21:30:10 2014 +0100
@@ -0,0 +1,66 @@
+package org.apidesign.math;
+
+/** Class to simplify arithmetical operations, improved version to compute
+ * the sum for ranges, but only if one uses the new constructor to indicate
+ * need for new version.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ * @version 2.0
+ */
+// BEGIN: design.composition.arith2.0.enum
+public class Arithmetica {
+    private final Version version;
+    public enum Version { VERSION_1_0, VERSION_2_0 }
+    
+    public Arithmetica() {
+        this(Version.VERSION_1_0);
+    }
+    public Arithmetica(Version version) {
+        this.version = version;
+    }
+
+    public int sumRange(int from, int to) {
+        switch (version) {
+            case VERSION_1_0:
+                return sumRange1(from, to);
+            case VERSION_2_0:
+                return sumRange2(from, to);
+            default:
+                throw new IllegalStateException();
+        }
+    }
+// FINISH: design.composition.arith2.0.enum
+    
+    public int sumTwo(int one, int second) {
+        return one + second;
+    }
+    
+    public int sumAll(int... numbers) {
+        if (numbers.length == 0) {
+            return 0;
+        }
+        int sum = numbers[0];
+        for (int i = 1; i < numbers.length; i++) {
+            sum = sumTwo(sum, numbers[i]);
+        }
+        return sum;
+    }
+    
+
+    private int sumRange1(int from, int to) {
+        int len = to - from;
+        if (len < 0) {
+            len = -len;
+            from = to;
+        }
+        int[] array = new int[len + 1];
+        for (int i = 0; i <= len; i++) {
+            array[i] = from + i;
+        }
+        return sumAll(array);
+    }
+    
+    private int sumRange2(int from, int to) {
+        return (from + to) * (Math.abs(to - from) + 1) / 2;
+    }
+}