ComClassAttribute Class

Definition

Namespace:

Microsoft.VisualBasic

Assembly:

Microsoft.VisualBasic.Core.dll

Source:

ComClassAttribute.vb

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

public ref class ComClassAttribute sealed : Attribute

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

[<System.AttributeUsage(System.AttributeTargets.Class, AllowMultiple=false, Inherited=false)>]
type ComClassAttribute = class
    inherit Attribute

Public NotInheritable Class ComClassAttribute
Inherits Attribute

Inheritance

Object

Attribute

ComClassAttribute

Attributes

AttributeUsageAttribute

Examples

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

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.

Constructors

ComClassAttribute()	Initializes a new instance of the ComClassAttribute class.
ComClassAttribute(String)	Initializes a new instance of the ComClassAttribute class.
ComClassAttribute(String, String)	Initializes a new instance of the ComClassAttribute class.
ComClassAttribute(String, String, String)	Initializes a new instance of the ComClassAttribute class.

Properties

ClassID	Gets a class ID used to uniquely identify a class.
EventID	Gets an event ID used to uniquely identify an event.
InterfaceID	Gets an interface ID used to uniquely identify an interface.
InterfaceShadows	Indicates that the COM interface name shadows another member of the class or base class.
TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• System.Runtime.InteropServices
• Attributes (Visual Basic)
• Applying Interop Attributes
• Walkthrough: Creating COM Objects with Visual Basic