Essential COM

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 void AssertStaticType(IUnknown *pUnk, REFIID riid) {      IUnknown *pUnk1 = 0, *pUnk2 = 0;     HRESULT hr1 = pUnk->QueryInterface(riid, (void**)&pUnk1);     HRESULT hr2 = pUnk->QueryInterface(riid, (void**)&pUnk2);       // both requests for the same interface should       // yield the same yes/no answer       //                  //              /     assert(SUCCEEDED(hr1) == SUCCEEDED(hr2));     if (SUCCEEDED(hr1)) pUnk1->Release();     if (SUCCEEDED(hr2)) pUnk2->Release(); } 

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1. , QueryInterface ( , IMorning ( ) 12:00).
2. , QueryInterface ( , INotBusy ( ), ).
3. (security token) , QueryInterface. 6, - (wire protocol), .
4. , QueryInterface ( , IHaveTonsOfMemory ( ) malloc(4096*4096)).

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 class   : public ICar, public IPlane, public IBoat {      enum TYPE { CAR, BOAT, PLANE, NONE };     TYPE m_type;     CBP(void) : m_type(NONE) { }      STDMETHODIMP QueryInterface(REFIID riid, void **ppv) {          if (md == IID_ICar) {            // 1st QI Initializes type of object            //   QI                    if (m_type == NONE) m_type = CAR;           // only satisfy request if this object is a car           //    ,                  //   car ( )             if (m_type == CAR)                 *ppv = static_cast<ICar*>(this);             else                 return (*ppv = 0), E_NOINTERFACE;         }         else if (md == IID_IBoat) {             // similar treatment for IBoat and IPlane             // IBoat   IPlane              } }; 

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