对象枚举遍历实现二

     //可枚举对象并非必须实现IEnumerable接口。该职责可以委托给第三个类来实现。
     public class Persons
    {  
         string[] m_Names;
         public Persons(params string[] Names)
         {
                m_Names = new string[Names.Length];
                Names.CopyTo(m_Names, 0);
         }
         private string this[int index]
         {
             get { return m_Names[index]; }
             set { m_Names[index] = value; }

         }
           
         private class PersonsEnumerator : IEnumerator
         {

           
            int index = -1;
            
            Persons p;
            public PersonsEnumerator(Persons p)
            {
                this.p = p;
            }
            public bool MoveNext()
            {
                index++;
                return index < p.m_Names.Length;
            }
            public void Reset()
            {
                index = -1;
            }
            public object Current
            {
                get
                {
                    return p.m_Names[index];
                }
            }
         }
         private class PersonsEnumerable : IEnumerable
         {
             private Persons m_persons;
             internal PersonsEnumerable(Persons persons)
             {
                 m_persons = persons;
             }
             IEnumerator IEnumerable.GetEnumerator()
             {
                 return new PersonsEnumerator(m_persons);
             }


         }
         public IEnumerable InOrder
         {
             get {   return new PersonsEnumerable(this); }
         }
         public IEnumerable Reverse
         {
             get 
             {
                 int length=this.m_Names.Length;
                 Persons persons= new Persons();
                 persons.m_Names = new string[length];
                 for (int i = 0; i < length; i++)
                 {
                    
                     persons.m_Names[i] = m_Names[length-i-1]; 
                 }
                 return new PersonsEnumerable(persons);

             }
         }
        
    }
       实现代码：
       public  static void EnumObject()
        {
            Persons p = new Persons("001","002","003");
            //正向输出
            foreach (string s in p.InOrder)
            {
                Console.WriteLine(s);
            }
            //反序输出
            foreach (string s in p.Reverse)
            {
                Console.WriteLine(s);
            }

        }