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title: "nonextensible | Microsoft Docs"
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---
# nonextensible
Specifies that the `IDispatch` implementation includes only the properties and methods listed in the interface description and cannot be extended with additional members at run time.  
  
## Syntax  
  
```  
  
[nonextensible]  
  
```  
  
## Remarks  
 The **nonextensible** C++ attribute has the same functionality as the [nonextensible](http://msdn.microsoft.com/library/windows/desktop/aa367120) MIDL attribute.  
  
 Use of **nonextensible** also requires the [oleautomation](../windows/oleautomation.md) attribute.  
  
## Example  
 The following code shows one use of the **nonextensible** attribute:  
  
```  
// cpp_attr_ref_nonextensible.cpp  
// compile with: /LD  
#include "unknwn.h"  
[module(name="ATLFIRELib")];  
[export] typedef long HRESULT;  
  
[dual, nonextensible, ms_union, oleautomation,   
uuid("00000000-0000-0000-0000-000000000001")]  
__interface IFireTabCtrl  
{  
   HRESULT procedure (int i);   
};  
```  
  
## Requirements  
  
### Attribute Context  
  
|||  
|-|-|  
|**Applies to**|`interface`|  
|**Repeatable**|No|  
|**Required attributes**|**dual** and **oleautomation**, or **dispinterface**|  
|**Invalid attributes**|None|  
  
 For more information about the attribute contexts, see [Attribute Contexts](../windows/attribute-contexts.md).  
  
## See Also  
 [IDL Attributes](../windows/idl-attributes.md)   
 [Interface Attributes](../windows/interface-attributes.md)