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ComClassAttribute Class

The ComClassAttribute attribute instructs the compiler to add metadata that allows a class to be exposed as a COM object.

<System.AttributeUsage(System.AttributeTargets.Class, _
   Inherited := False, AllowMultiple := False)> _
Public NotInheritable Class ComClassAttribute
   Inherits System.Attribute


Use ComClassAttribute to simplify the process of exposing COM components from Visual Basic. COM objects are very different from .NET Framework assemblies; without the ComClassAttribute, you need to follow a number of steps to generate a COM object from Visual Basic. For classes marked with ComClassAttribute, the compiler performs many of these steps automatically.


This attribute simplifies the creation of COM objects. To expose a class as a COM object, you must compile the project with the Register for COM Interop option selected in the Build section of the Configuration Properties dialog box.


Although you can also expose a class created with Visual Basic as a COM object for unmanaged code to use, it is not a true COM object. For details, see COM Interoperability in .NET Framework Applications.


To run this example, create a new Class Library application and add the following code to a class module.

    <ComClass(ComClass1.ClassId, ComClass1.InterfaceId, ComClass1.EventsId)> _
    Public Class ComClass1
        ' Use the Region directive to define a section named COM Guids. 
#Region "COM GUIDs" 
        ' These  GUIDs provide the COM identity for this class  
        ' and its COM interfaces. You can generate  
        ' these guids using guidgen.exe 
        Public Const ClassId As String = "7666AC25-855F-4534-BC55-27BF09D49D46" 
        Public Const InterfaceId As String = "54388137-8A76-491e-AA3A-853E23AC1217" 
        Public Const EventsId As String = "EA329A13-16A0-478d-B41F-47583A761FF2"
#End Region

        Public Sub New()
        End Sub 

        Function AddNumbers(ByVal X As Integer, ByVal Y As Integer)
            AddNumbers = X + Y
        End Function 
    End Class



Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

See Also


Walkthrough: Creating COM Objects with Visual Basic


Applying Interop Attributes

Attributes Used in Visual Basic


ComClassAttribute Class Members

VBFixedArrayAttribute Class

VBFixedStringAttribute Class


Other Resources

Attributes in Visual Basic