Wrap .Net ArrayList with custom VBA class get iterator

Question

I just discovered that I can create some .Net classes from VBA using the CreateObject method which can create COM classes. This is pretty cool but the created class is late

Answer 1

When you use

 Dim enumerator As Object

you are declaring a COM object. But COM implements IEnumerator as IEnumVARIANT, which inherits IUnknown directly, and COM is not happy trying to set the GetEnumerator return value into an Object. Instead, you can use

Dim enumerator As IEnumVARIANT

EDIT: Note that although ArrayList implements IEnumerable, it overloads GetEnumerator with a method that takes index and count. So you have to use the Nothing keyword in VBA when you want to call the overload with no parameters.

Set iterator = list.GetEnumerator(Nothing, Nothing)

You can see that it's working, because if you include your original lines of code that add two items to the list, and then use a call such as

Set iterator = list.GetEnumerator(1, 3) ' 3 is out of bounds

you now get a new (expected) error informing you that offset/length are out of bounds.