peterchen - Professional Profile

// ==============================================================
//  CRefcountableBase   
// --------------------------------------------------------------
/// This class allows to reuse _com_ptr_t smart pointers for 
/// generic C++ classes.
/// Inherit the class to be refcounted from CRefCountableBaseST
/// for single threaded, or CRefCountableBaseMT for thread-safe refcounting.
/// use CPP_SMARTPTR_TYPEDEF(CMyClass) to declare the CMyClassPtr smart pointer.
//  

template <class ThreadModel = CComSingleThreadModel>
class CRefCountableBase 
{
private:
   LONG     _ref;

public:

   CRefCountableBase()
   {
      _ref = 0;
   }

   ~CRefCountableBase()
   {
      _ASSERTE(_ref == 0);
   }

   ULONG AddRef()
   {
      return ThreadModel::Increment(&_ref);
   }

   ULONG Release()
   {
      LONG zero = ThreadModel::Decrement(&_ref);
      if (zero == 0)
         delete this;
      return zero;
   }

   HRESULT QueryInterface(REFIID riid, void ** ppvObject)
   {
      return E_NOTIMPL;
   }

   template <class T>
   static void CreateInstance(_com_ptr_t< _com_IIID<T, &GUID_NULL> > & ptr)
   {
      T * instance = new T;
      if (instance == 0)
         return;
      ptr.Attach(instance, true);
   }

};

typedef CRefCountableBase<CComSingleThreadModel> CRefCountableBaseST;
typedef CRefCountableBase<CComMultiThreadModel>  CRefCountableBaseMT;

#define CPP_SMARTPTR_TYPEDEF(CLASS)  \
            typedef _com_ptr_t< _com_IIID<CLASS, &GUID_NULL> > CLASS ## Ptr;