COM

// Must have more than 1 inderection of pointer<br />
// In idl-file [...] HRESULT OneStudent([out,retval]IStudent* *pVal);<br />
STDMETHODIMP CTeacher::get_OneStudent(IStudent* *pVal)<br />
{<br />
  AFX_MANAGE_STATE(AfxGetStaticModuleState())<br />
  // TODO: Add your implementation code here<br />
  *pVal = m_aStudent;<br />
  if( m_aStudent != NULL )<br />
    m_aStudent->AddRef();<br />
  return S_OK;<br />
}<br />
<br />
// In idl-file [...] HRESULT OneStudent([in]IStudent* newVal);<br />
STDMETHODIMP CTeacher::put_OneStudent(IStudent *newVal)<br />
{<br />
  AFX_MANAGE_STATE(AfxGetStaticModuleState())<br />
  // TODO: Add your implementation code here<br />
  if( m_aStudent != NULL )<br />
    m_aStudent->Release();<br />
  m_aStudent = newVal ;<br />
  if( m_aStudent != NULL )<br />
    m_aStudent->AddRef();<br />
  return S_OK;<br />
}<br />

Set s = t.OneStudent<br />

#include <stdio.h>
#include <windows.h>
#include "comdef.h"
#include "atlbase.h"

void main()
{
	CoInitialize(0);
	{
		CComPtr<IDispatch> p;
		HRESULT hr;

		hr = p.CoCreateInstance(L"TestObj.Test");
		if(S_OK == hr)
		{
			
			::ITypeInfo *pti;
			::ITypeLib *ptl;
			UINT ui;

			hr = p->GetTypeInfo(0, LOCALE_SYSTEM_DEFAULT,&pti);
			
			if(S_OK == hr)
			{
				hr = pti->GetContainingTypeLib( &ptl, &ui);
				pti->Release();
				if(S_OK == hr)
				{
					ui = ptl->GetTypeInfoCount();
					
					for(UINT i = 0; i < ui; ++i)
					{
						hr = ptl->GetTypeInfo(i, &pti);
						
						
						if(S_OK == hr)
						{
							
							::TYPEATTR *patr = 0;
							hr = pti->GetTypeAttr( &patr);
							if(patr->typekind == TKIND_COCLASS)
							{
								printf("OK - TKIND_COCLASS\n");
								OLECHAR *wsz;
								hr = ::StringFromCLSID(patr->guid, &wsz);
								
								if(S_OK == hr)
								{
									printf("CLSID = %s\n",(char*) _bstr_t(wsz));
									::CoTaskMemFree(wsz);
								}
							}
							pti->Release();
						}
					}
					ptl->Release();
					
				}
			}
		}
	}
	CoUninitialize();
}

// IDL source for prj1.dll
//

// This file will be processed by the MIDL tool to
// produce the type library (prj1.tlb) and marshalling code.

import "oaidl.idl";
import "ocidl.idl";

[
	uuid(XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX), // GUID of your Type Library. Use GUIDGEN.EXE from MS Common\Tools
	version(n.m),                               // Version of your Type Library, e.g. 1.0 
	helpstring("XXXXXXXX")                      // Description of your Type Library
]
library XXXXLib                               // Name of your Type Library
{
	importlib("stdole32.tlb");
	importlib("stdole2.tlb");

typedef [
	uuid(XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX), // GUID of your Enum. Use GUIDGEN.EXE from MS Common\Tools
	version(n.m),                               // Version of your Enum, e.g. 1.0 
	helpstring("XXXXXXXX")                      // Description of your Enum
]
enum tagXXXX                                  // Name of your Enum
{
	[helpstring("XXXXXXXX")]                        // Description of your Enum Value
	XXXX = YYYY,                                    // Name and Value (optional as C++) of your Enum Value
//	and so on ...
} XXXX;                                       // Name of your Enum

typedef [
	uuid(XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX), // GUID of your Struct. Use GUIDGEN.EXE from MS Common\Tools
	version(n.m),                               // Version of your Struct, e.g. 1.0 
	helpstring("XXXXXXXX")                      // Description of your Struct
]
struct tagXXXX                                // Name of your Struct
{
  // your struct (as C++)
} XXXX;                                       // Name of your Struct

};

   typedef [uuid(XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX), helpstring("Help")] 
   struct _SomeStruct
   {
      int i;
      BSTR str;
...
   } SomeStruct;

   [...,dual,...]
   interface IO : IDispatch
   {
      [id(1)] HRESULT M1([in] SomeStruct ss);
      [id(2)] HRESULT M2([in,out] SomeStruct *ss);
      [id(3)] HRESULT M3([out,retval] SomeStruct* *ss);
      [id(4)] HRESULT M4([in,out] SAFEARRAY(SomeStruct) * ssbs);
   };