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
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
Concepts
Attributes Used in Visual Basic
Reference
ComClassAttribute Class Members
System.Runtime.InteropServices