Instructions

class OuterCOMObj_ClassFactory : IClassFactory {
...
  HRESULT CreateInstance
    (IUnknown *po, REFIID riid, void **ppv)   {
    BOOL bInit;
    HRESULT hr = E_FAIL;
     //Create the COM object
     OuterCOMObj *pcom = new OuterCOMObj();
     if (!pcom) return E_OUTOFMEMORY;

     //Call the Init method. This is NOT a COM call.  
     //It is simply an internal initialization call.
     bInit = pcom->Init();
     if (bInit) hr = pcom->QueryInterface(riid, ppv);

     if (FAILED(hr) || !bInit) delete pcom;

     return hr;
   }
   ... Other Code ...
 };

 
class OuterCOMObj : IX1, IX2 {
  ULONG m_refcnt;
  IX1 *m_pInner_IX1;

public:
  OuterCOMObj() : m_refcnt(0), 
     pInner_IX1(NULL) { }
   ~OuterCOMObj { }

  //Called from IClassFactory::CreateInstance to perform internal initialization of the COM 
  //object. This is where the outer COM object
  //creates an instance of the inner COM object 
  //and gets an interface pointer into it.
  
  BOOL Init()  {
  //Create an instance of the inner COM object 
  //and get a pointer to its IX1 interface.
  //Place the inner COM object's IX1 pointer 
  //in m_pInner_IX1.
     
      HRESULT hr = 
         CoCreateInstance(CLSID_InnerCOMObj, 
            NULL, CLSCTX_INPROC_SERVER,
            IID_IX1, (void **) &m_pInner_IX1);

      if (FAILED(hr)) return FALSE;
       return TRUE;
 }

 HRESULT QueryInterface(REFIID riid, void **ppv) {
    if (riid == IID_IX1)   *ppv = (IX1 *) this;
    if (riid == IID_IX2)   *ppv = (IX2 *) this;
    else return E_NOINTERFACE;
       
    ((IUnknown *) (*ppv))->AddRef();
    return S_OK;
}

 HRESULT AddRef() { return ++m_refcnt; }
 HRESULT Release()  {
      if (--m_refcnt == 0) {
         delete this;
         return 0;
       }
       return m_refcnt;
   }
  //IX1 Functions
  HRESULT x1(int ix) {
      //Delegate to the inner object's IX1::x1
      return m_pInner_IX1->x1(zz);
  }
  //x2 filters it delegation - calling into the 
  //inner object every other time
  HRESULT x2() {                
     static int even_odd = 1;
     HRESULT hr = S_OK;    
     if (!(even_odd % 2))      {
        //Delegate to the inner object's IX1::X2
        hr = m_pInner_IX1->x2();
     }
     else { ... do stuff ..    }
     ++even_odd;
     return hr;
   }

   //IX2 Functions
  Assume IX2 is an interface implemented 
  by the outer COM object. For this exercise 
  we are not concerned with its implementation.
};