Marshal.CreateWrapperOfType Method

Wraps the specified COM object in an object of the specified type.

Namespace: System.Runtime.InteropServices
Assembly: mscorlib (in mscorlib.dll)

public static Object CreateWrapperOfType (
	Object o,
	Type t
public static Object CreateWrapperOfType (
	Object o, 
	Type t
public static function CreateWrapperOfType (
	o : Object, 
	t : Type
) : Object
Not applicable.



The object to be wrapped.


The Type of wrapper to create.

Return Value

The newly wrapped object that is an instance of the desired type.

Exception typeCondition


t must derive from __ComObject.


The t parameter is a null reference (Nothing in Visual Basic).


o cannot be converted to the destination type since it does not support all required interfaces.

CreateWrapperOfType converts one COM class type, typically the generic __ComObject type, to another COM class type. The input COM object, represented by parameter o, is a runtime callable wrapper. If you are unfamiliar with this wrapper, see Runtime Callable Wrapper.

Both the t and o parameters must be classes whose signatures are attributed with System.Runtime.InteropServices.ComImportAttribute. The Type Library Importer (Tlbimp.exe) applies this attribute for you when it imports a type library. If you create the runtime callable wrapper manually in source code, you should apply this attribute to the managed signature representing the original coclass to signify its COM origins.

Tlbimp.exe imports a COM coclass as a managed class and an interface. The coclass interface has the same name as the original coclass and the managed class has the original coclass name appended with Class. For example, a coclass called MyCoclass becomes a coclass interface called MyCoclass and a managed class called MyCoclassClass. Since t must be a class, not an interface, be sure to specify the managed class (MyCoclassClass) and not the coclass interface.


You lose the identity of the input COM object because a new runtime callable wrapper instance wraps the IUnknown pointer exposed by the original runtime callable wrapper.


This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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