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ComClassAttribute Class 

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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

Remarks

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.

Note

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.

Note

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.

Example

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()
            MyBase.New()
        End Sub

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

Requirements

Namespace: Microsoft.VisualBasic

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

See Also

Tasks

Walkthrough: Creating COM Objects with Visual Basic 2005

Reference

ComClassAttribute Class Members
VBFixedArrayAttribute Class
VBFixedStringAttribute Class
System.Runtime.InteropServices

Concepts

Applying Interop Attributes
Attributes Used in Visual Basic

Other Resources

Attributes in Visual Basic