Question

Are shared properties accessible from a COM exposed .NET assembly?

VBA

Dim appExcel As Object
    Dim objAppSingleton As Object
    Set objAppSingleton = CreateObject("Pitchbook.CommonUtils.Application.PitchbookAppSingleton")
    appExcel = objAppSingleton.CurrentPitchbookExcelApp

VB.NET

<ProgId("Pitchbook.CommonUtils.Application.PitchbookAppSingleton")> _
Public Class PitchbookAppSingleton

    Private Shared _currentPitchbookExcelApplication As PitchbookAppExcel
    Private Shared _syncLockExcel As Object = New Object()

   Public Shared ReadOnly Property CurrentPitchbookExcelApp As PitchbookAppExcel
        Get
            If _currentPitchbookExcelApplication Is Nothing Then
                                    SyncLock [_syncLockExcel]
                    If _currentPitchbookExcelApplication Is Nothing Then
                        Dim currPitchbookExcelApplication As New PitchbookAppExcel()
                        _currentPitchbookExcelApplication = currPitchbookExcelApplication
                    End If
                End SyncLock
            End If
            Return _currentPitchbookExcelApplication
        End Get
    End Property

End Class


Public Class PitchbookAppExcel
    Inherits PitchbookApp

    Protected Friend Sub New()
        MyBase.New()                        
    End Sub

End Class

The line appExcel = objAppSingleton.CurrentPitchbookExcelApp gives the error:
Run-time error ‘438’:
Object doesn’t support this property or method

Answer 1

This is a very simple problem but if anyone doesn’t know the answer already it’s no you cannot access shared properties from a COM exposed .NET assembly. At least not directly… you can however access shared properties if you create an instance wrapper.

http://www.xtremevbtalk.com/showthread.php?p=1326018
http://support.microsoft.com/Default.aspx?kbid=817248

In my case I used the Facade pattern to create an object specifically for use by VBA that exposed the relevant shared utility functions via instances. Thanks to everyone for their comments.
http://en.wikipedia.org/wiki/Facade_pattern