Create VBA class in VB.net - vb.net

Question

Is it possible (using COM and regasm.exe) to have a vba function call a vb.net function - which creates the class in vb.net and then passes the class back to vba, where it is recognised as a vba class?
In VBA, I can work with classes by using Insert>Class Module. I have set up a function that creates a class.
Private length As Double
Private height As Double
Public Sub init(ByRef hgt As Double)
height = hgt
length = dbl_height()
End Sub
Public Function dbl_height()
dbl_height = height * 2
End Function
I can initialize it accordingly using this function:
Public Function CreateClassFunction(foo As Integer)
Dim my_rect As Rectangle
Set my_rect = New Rectangle
my_rect.init (foo)
Set CreateClassFunction = my_rect
End Function
I can also do the same thing in vb.net with virtually identical code.
Public Class Rectangle
Private length As Double
Private height As Double
Public Sub init(ByRef hgt As Double)
height = hgt
length = dbl_height()
End Sub
Public Function dbl_height()
dbl_height = height * 2
End Function
End Class
where this vb.net function creates the class:
Public Function CreateClassFunction(foo As Integer) As Rectangle
Dim my_rect As Rectangle
my_rect = New Rectangle
my_rect.init(foo)
CreateClassFunction = my_rect
End Function
I can pull in a Variant/Object/Rectangle into vba using:
Function MyCreateClass(a As Double)
Dim classLib As New MyAnalytics.Class1
Set MyCreateClass = classLib.CreateClassFunction(a)
End Function
However this object does not have the height or length variables. (It says "no variables" on the watch window)
Edit:
Amended code as per Mat's Mug answer:
Public Class Rectangle
Private plength As Double
Private pheight As Double
Public Property length() As Double
Get
Return plength
End Get
Set(ByVal value As Double)
plength = value
End Set
End Property
Public Property height() As Double
Get
Return pheight
End Get
Set(ByVal value As Double)
pheight = value
End Set
End Property
Public Sub init(ByRef hgt As Double)
height = hgt
length = dbl_height()
End Sub
Public Function dbl_height()
dbl_height = height * 2
End Function
End Class
and testing in VBA:
Function MyCreateClass(a As Double)
Dim classLib As New MyAnalytics.Class1
Set MyCreateClass = classLib.CreateClassFunction(a)
Debug.Print MyCreateClass.Height()
Debug.Print MyCreateClass.length()
MyCreateClass.Height = 30
MyCreateClass.length = 20
Debug.Print MyCreateClass.Height()
Debug.Print MyCreateClass.length()
MyCreateClass.init (100)
Debug.Print MyCreateClass.Height()
Debug.Print MyCreateClass.length()
End Function

Answer 1

It won't be recognized as a VBA class - it's not a VBA class, but a COM object.
Your Rectangle class has private fields. Private fields are, well, Private. This is, roughly, what VBA sees:
Public Class Rectangle
Sub init(ByRef hgt As Double)
Function dbl_height()
End Class
Where are the fields?
Private length As Double
Private height As Double
You haven't exposed them - as far as VBA goes, they don't exist.
Now, you could make them Public - but then you would be breaking encapsulation by exposing fields; don't do that!
Expose property getters instead, and setters if you want VBA code to be able to change the Length and Height properties of a Rectangle instance.