You can find here the
code. It is a VS2008 solution file. Just use the .vb classes if you don't have VS2008 to open up the solution
I have already shown in my previous post how to create COM interop assembly in VB.NET and in C#.
You can have a look
here and
here. For More more detailed info please look also
here
where you will find plenty of details on the how COM dll development and deployment works.
I will try to summarize some important point relevant to the VB.NET developer using the COM template here
1) The COM template automatically ticks for you
Compile / Register for COM interop
Application / Assembly Infomation... / Make assembly COM Visible
The second option is actually a bed idea, becuase it will register for COM all the types you declare in the assembly. If you have some assembly without the GUID it will create them for you generating a registry bloat.
So each time you add a COM Template, go and untick Make assembly COM-Visible.
Once you have done that you need to add
as class attributes. (see the code)
2) If you define a Default Property, this will become a default property for your COM object as well. You can also have indexed properties. The ComClassAttribute will associate to it a DispId(0)
3) if you define a GeEnumerator() function that return a IEnumerator than you will enable the For Each ... Next
loop in VBA. ComClassAttribute will associate to it a DispId(-4)
Public Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
End Function
4) Also public events are exposed.
The code will show you how to create a Collection with a default property and the For Each ... Next loop enabled and how to expose and event.
Employee Class
Imports System.Runtime.InteropServices
<ComClass(Employee.ClassId, Employee.InterfaceId, Employee.EventsId), _
ComVisible(True)> _
Public Class Employee
#Region "COM GUIDs"
' These GUIDs provide the COM identity for this class
' and its COM interfaces. If you change them, existing
' clients will no longer be able to access the class.
Public Const ClassId As String = "dd3ef2f6-261f-477d-af54-10abc39a07d9"
Public Const InterfaceId As String = "a0680708-b5ca-4679-8e8e-1b012479b8ee"
Public Const EventsId As String = "d7361527-7a80-4e47-9aff-4e603a26812b"
#End Region
' A creatable COM class must have a Public Sub New()
' with no parameters, otherwise, the class will not be
' registered in the COM registry and cannot be created
' via CreateObject.
Public Sub New()
MyBase.New()
End Sub
Private _Name As String
Public Property Name() As String
Get
Return _Name
End Get
Set(ByVal value As String)
_Name = value
End Set
End Property
End Class
Employer Class
Imports System.Runtime.InteropServices
<ComClass(Employer.ClassId, Employer.InterfaceId, Employer.EventsId), _
ComVisible(True)> _
Public Class Employer
#Region "COM GUIDs"
' These GUIDs provide the COM identity for this class
' and its COM interfaces. If you change them, existing
' clients will no longer be able to access the class.
Public Const ClassId As String = "a0513ce8-fac4-4187-8190-0584f59cda1e"
Public Const InterfaceId As String = "2c55f846-2dc9-4f0f-9b82-5e16dfefee52"
Public Const EventsId As String = "2f99d8e4-afe8-46ef-a4e0-d62b4db18a4d"
#End Region
' A creatable COM class must have a Public Sub New()
' with no parameters, otherwise, the class will not be
' registered in the COM registry and cannot be created
' via CreateObject.
Public Sub New()
MyBase.New()
End Sub
Public Event OnNameChange(ByRef newName As String)
Private _Name As String
Public Property Name() As String
Get
Return _Name
End Get
Set(ByVal value As String)
RaiseEvent OnNameChange(value)
_Name = value
End Set
End Property
End Class
Collection Class
Imports System.Runtime.InteropServices
<ComClass(MyCol.ClassId, MyCol.InterfaceId, MyCol.EventsId), _
ComVisible(True)> _
Public Class MyCol
Implements IEnumerable
#Region "COM GUIDs"
' These GUIDs provide the COM identity for this class
' and its COM interfaces. If you change them, existing
' clients will no longer be able to access the class.
Public Const ClassId As String = "994ba5ce-1301-455b-9334-409e28aea0c3"
Public Const InterfaceId As String = "87280e58-8be8-40f8-8987-d3fac317c6c3"
Public Const EventsId As String = "11d12ead-4562-4ab1-a04b-5ef7fa9fba4c"
#End Region
' A creatable COM class must have a Public Sub New()
' with no parameters, otherwise, the class will not be
' registered in the COM registry and cannot be created
' via CreateObject.
Dim _SortedList As SortedList
Public Sub New()
MyBase.New()
_SortedList = New SortedList
End Sub
Default Public Property Item(ByVal key As Object)
Get
Return _SortedList(key)
End Get
Set(ByVal value)
_SortedList(key) = value
End Set
End Property
Public ReadOnly Property Count()
Get
Return _SortedList.Count
End Get
End Property
Public Sub Remove(ByVal key As Object)
_SortedList.Remove(key)
End Sub
Public Sub Add(ByVal key As Object, ByVal value As Object)
_SortedList.Add(key, value)
End Sub
Public Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
'Return _SortedList.GetEnumerator()
Dim keys As ICollection = _SortedList.Keys
Return CType(keys.GetEnumerator, IEnumerator)
End Function
End Class
VBA Code to test the class
Option Explicit
Dim WithEvents a As TestCOMVisible01.Employer
Sub prova()
If a Is Nothing Then
Set a = New TestCOMVisible01.Employer
End If
a.Name = "Gino"
Debug.Print a.Name
Dim emp1 As New TestCOMVisible01.Employee
Dim emp2 As New TestCOMVisible01.Employee
Dim col As New TestCOMVisible01.MyCol
emp1.Name = "mario"
emp2.Name = "pluto"
Call col.Add("1", emp1)
Call col.Add("2", emp2)
Dim key As Variant
For Each key In col
Debug.Print col(key).Name
Next
End Sub
Private Sub a_OnNameChange(newName As String)
newName = "ho cambiato il nome"
End Sub
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