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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

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