C # enumerated class - compatible with VBA

Question

Can someone instruct me on how to encode an enumerated C # class so that the "for each" construct works correctly in Excel VBA? I tried this with the People test class, which implements IEnumerable and contains an array of Person objects. The foreach construct works fine in C #, but in VBA I can only loop in the old fashioned way.

This VBA code works very well:

Dim P As Person
Dim PP As New People

For i = 0 To PP.Count - 1
    Set P = PP(i)
    Debug.Print P.firstName + " " + P.lastName
Next i

But this fails at runtime ("The object does not support this property or method"):

For Each P In PP
    Debug.Print P.firstName + " " + P.lastName
Next P

Here is the C # code (compiled COM visible in VS 2008 for use with Excel VBA - Office 2010):

using System;
using System.Collections;
using System.Runtime.InteropServices;

public class Person
{
    public Person(string fName, string lName)
    {
        this.firstName = fName;
        this.lastName = lName;
    }
    public string firstName;
    public string lastName;
}

public class People : IEnumerable
{
    private Person[] _people;                           // array of people
    public Int32 Count() { return _people.Length; }     // method to return array size

    // indexer method to enable People[i] construct, or in VBA: People(i)
    public Person this[Int32 PersonNo] { get { return _people[PersonNo]; } }

    // constructor - hardcode to initialize w 3 people (for testing)
    public People()
    {
        _people = new Person[3]
        {
            new Person("John", "Smith"),
            new Person("Jim", "Johnson"),
            new Person("Sue", "Rabon"),
        };
    }

    // test method just to make sure the c# foreach construct works ok
    public void Test() 
    { 
        foreach (Person P in this) System.Diagnostics.Debug.WriteLine(P.firstName + " " + P.lastName); 
    }

    //implementation of basic GetEnumerator
    IEnumerator IEnumerable.GetEnumerator()
    {
        return (IEnumerator)GetEnumerator();
    }

    //implementation of People GetEnumerator
    public PeopleEnum GetEnumerator()
    {
        return new PeopleEnum(_people);
    }
}

// People Enumerator class definition
public class PeopleEnum : IEnumerator
{
    public Person[] _people;

    int position = -1;

    public PeopleEnum(Person[] list)
    {
        _people = list;
    }

    public bool MoveNext()
    {
        position++;
        return (position < _people.Length);
    }

    public void Reset()
    {
        position = -1;
    }

    object IEnumerator.Current
    {
        get
        {
            return Current;
        }
    }

    public Person Current
    {
        get
        {
            try
            {
                return _people[position];
            }
            catch (IndexOutOfRangeException)
            {
                throw new InvalidOperationException();
            }
        }
    }
}

Answer 1

[DispId(-4)] GetEnumerator(). , DISPID_NEWENUM. VBA , For Every, _ newEnum COM.

, Enumerator DispId. , .