IEnumerable does not allow access to sub items

Question

To make a long story short. I have the following code:

class MyList : IEnumerable
{
    private List<string> T1 = new List<string>();
    private List<string> T2 = new List<string>();
    private List<string> T3 = new List<string>();
    public List<string> Name { set { T1 = value; } get { return T1; } }
    public List<string> DataType { set { T2 = value; } get { return T2; } }
    public List<string> Nullable { set { T3 = value; } get { return T3; } }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return (IEnumerator)GetEnumerator();
    }
    public MyList<List<string>, List<string>, List<string>> GetEnumerator()
    {
        return new MyList<List<string>, List<string>, List<string>>(T1, T2, T2);
    }
}

What I want is to access it like this:

       MyList ml = new MyList();
       foreach (var item in ml)
       {
           str = item.Name;
       }

It does not let me access the subitem, like item.Name, or item.DataType.

Answer 1

If you really want to expose the functionality you describe (3 lists collectively representing a set of items) you can do it, but you still need to expose a new type for the benefit of your enumerator.

class MyItem 
{
    public string Name { get; set; }
    public string DataType { get; set; }
    public bool Nullable { get; set; }
}

class MyList : IEnumerable<MyItem>
{
    public List<string> Names { get; set; }
    public List<string> DataTypes { get; set; }
    public List<bool> Nullables { get; set; }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }

    public IEnumerator<MyItem> GetEnumerator()
    {
        // assuming all lists are the same length
        for (int i = 0; i < Names.Count; i++)
            yield return new MyItem {
                Name = Names[i],
                DataType = DataTypes[i],
                Nullable = Nullables[i]
            };
    }
}

Now you can do:

MyList ml = new MyList();
ml.Names = new [] { "AccountNum", "Value", "Owner" } .ToList();
ml.DataTypes = new [] { "nvarchar(50)", "decimal(14,6)", "nvarchar(50)" } .ToList();
ml.Nullables = new [] { false, false, true } .ToList();

foreach (var item in ml)
{
    str = item.Name;
}