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接上篇http://www.cnblogs.com/Clingingboy/archive/2011/06/14/2081019.html

一.封裝生命周期步驟

由于以上過程容易出錯,所以在CComCreator 對其生命周期調用進行了封裝

template <class T1> class CComCreator { public:_Success_(return == S_OK) static HRESULT WINAPI CreateInstance(_In_opt_ void* pv, _In_ REFIID riid, _Deref_out_ LPVOID* ppv){ATLASSERT(ppv != NULL);if (ppv == NULL)return E_POINTER;*ppv = NULL;HRESULT hRes = E_OUTOFMEMORY;T1* p = NULL;ATLPREFAST_SUPPRESS(6014)/* prefast noise VSW 489981 */ATLTRY(p = new T1(pv)) ATLPREFAST_UNSUPPRESS()if (p != NULL){p->SetVoid(pv);p->InternalFinalConstructAddRef();hRes = p->_AtlInitialConstruct();if (SUCCEEDED(hRes))hRes = p->FinalConstruct();if (SUCCEEDED(hRes))hRes = p->_AtlFinalConstruct();p->InternalFinalConstructRelease();if (hRes == S_OK)hRes = p->QueryInterface(riid, ppv);if (hRes != S_OK)delete p;}return hRes;} };

現在創建對象又簡化了一些

class CPenguin : ... { public:...typedef CComCreator<CComPolyObject<CPenguin> > _CreatorClass; }; STDMETHODIMP CAviary::CreatePenguin(IBird** ppbird) {return CPenguin::_CreatorClass::CreateInstance(0,IID_IBird,(void**)ppbird); }

二.使用CComCoClass 進一步簡化

由于CreateInstance方法很常用,進一步簡化就是繼承一個既有封裝好的類,就是CComCoClass,其實現方式是一樣的

template <class T, const CLSID* pclsid = &CLSID_NULL> class CComCoClass { public: ... template <class Q> static HRESULT CreateInstance(IUnknown* punkOuter, Q** pp) {return T::_CreatorClass::CreateInstance(punkOuter, __uuidof(Q), (void**) pp); } template <class Q> static HRESULT CreateInstance(Q** pp) { return T::_CreatorClass::CreateInstance(NULL, __uuidof(Q), (void**) pp); } };

三.用宏簡化CComCreator的創建

#define DECLARE_POLY_AGGREGATABLE(x) public:\ typedef ATL::CComCreator< \ ATL::CComPolyObject< x > > _CreatorClass;

現在簡化成這樣(或者將DECLARE_AGGREGATABLE放在CComCoClass內部)

class CPenguin : public CComCoClass<CPenguin, &CLSID_CPenguin> { public:...DECLARE_AGGREGATABLE(CPenguin) };

四.是否支持聚合(CComFailCreator)

轉載于:https://www.cnblogs.com/Clingingboy/archive/2011/06/15/2081782.html

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