VBA - Calling a function which accepts parent object as variable

Question

Is it possible to create a function which accepts it's parent object as a variable? I suppose the simplest way to illustrate what I'm talking about is to provide an example:

Module 1 Code:

Function IsProduct() as Boolean
    IsProduct = (vartype(Parent.Value) <> vbEmpty)
End Function
' "Parent" in this case would be a Range '

Module 2 Code:

Dim myRng as Range
If myRng.IsProduct Then Debug.Print "'Tis a product, sir."

Answer 1

I did not fully understand your question; as far as I know you cannot extend existing classes with methods in VBA. Maybe you want something like this?

Module 1:

Function IsProduct(parent As Object) as Boolean
    IsProduct = (vartype(parent.Value) <> vbEmpty)
End Function
' This can take a Range as well as other objects as a parameter

Module 2:

Dim myRng as Range
If IsProduct(myRng) Then Debug.Print "'Tis a product, sir."

Answer 2

You would use the Me keyword inside a class to refer to the class. Like

IsProduct = IsEmpty(Me.Value)

You can simulate extending native classes in VBA. Create a class called cRange and give it two properties: Range and IsProduct

Private mclsRange As Range

Private Sub Class_Terminate()

    Set mclsRange = Nothing

End Sub

Public Property Get Range() As Range

    Set Range = mclsRange

End Property

Public Property Set Range(clsRange As Range)

    Set mclsRange = clsRange

End Property

Public Property Get IsProduct() As Boolean

    IsProduct = IsEmpty(Me.Range.Value)

End Property

Now you can use the Range property to get to all the built in properties and methods of the native Range object, and create any other properties (like IsProduct) that you want.