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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.

Namespace:   Microsoft.VisualBasic
Assembly:  Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)


[AttributeUsageAttribute(AttributeTargets.Class, Inherited = false, 
	AllowMultiple = false)]
public sealed class ComClassAttribute : Attribute


Initializes a new instance of the ComClassAttribute class.


Initializes a new instance of the ComClassAttribute class.

System_CAPS_pubmethodComClassAttribute(String, String)

Initializes a new instance of the ComClassAttribute class.

System_CAPS_pubmethodComClassAttribute(String, String, String)

Initializes a new instance of the ComClassAttribute class.


Gets a class ID used to uniquely identify a class.


Gets an event ID used to uniquely identify an event.


Gets an interface ID used to uniquely identify an interface.


Indicates that the COM interface name shadows another member of the class or base class.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from 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 (Visual Basic).

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

.NET Framework
Available since 1.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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