c# extensions

c# Example found on the net, demonstrated how Dot Net 3 extensions are declared and consumed.

namespace myExtensionExample
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] values = { 5, 6, 10 };

            bool isInArray = 7.In(values);

            string[] s_vals = { "5", "6", "10" };
            bool isInStringArray = "10".In(s_vals);

            string s = "Hello Extension Methods";
            int i = s.WordCount();
        }
    }

    //define extension methods within a static class
    public static class myExtensions
    {
        //'this' parameter is usually used on object where the method is applied to
        public static int WordCount(this string str)
        {
            return str.Split(new char[] { ' ', '.', '?' }, StringSplitOptions.RemoveEmptyEntries).Length;
        }
        public static bool In(this T o, IEnumerable items)
        {
            foreach (T item in items)
            {
                if (item.Equals(o))
                    return true;
            }
            return false;
        }
    }
}

Original materials from http://msdn.microsoft.com/en-us/library/bb383977.aspx