IUnknownConstantAttribute Class
Indicates that the default value for the attributed field or parameter is an instance of UnknownWrapper, where the WrappedObject is a null reference (Nothing in Visual Basic).
For a list of all members of this type, see IUnknownConstantAttribute Members.
System.Object
System.Attribute
System.Runtime.CompilerServices.CustomConstantAttribute
System.Runtime.CompilerServices.IUnknownConstantAttribute
[Visual Basic] <AttributeUsage(AttributeTargets.Field Or _ AttributeTargets.Parameter)> <Serializable> NotInheritable Public Class IUnknownConstantAttribute Inherits CustomConstantAttribute [C#] [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter)] [Serializable] public sealed class IUnknownConstantAttribute : CustomConstantAttribute [C++] [AttributeUsage(AttributeTargets::Field | AttributeTargets::Parameter)] [Serializable] public __gc __sealed class IUnknownConstantAttribute : public CustomConstantAttribute [JScript] public AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter) Serializable class IUnknownConstantAttribute extends CustomConstantAttribute
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Remarks
You can apply this attribute to fields or parameters.
The type library importer uses this attribute to distinguish a default value of type VT_UNKNOWN from a null reference (Nothing in Visual Basic).
For more information about constant attributes, see the CustomConstantAttribute class.
The classes in System.Runtime.CompilerServices are for compiler writers use only.
Requirements
Namespace: System.Runtime.CompilerServices
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
Assembly: Mscorlib (in Mscorlib.dll)
See Also
IUnknownConstantAttribute Members | System.Runtime.CompilerServices Namespace