FAQ: 如何动态创建一个IDispatch接口

Question

问：如题

Answer 1

2002年我曾经碰到过这个问题。答：
    为某个类的一个(目前只支持一个)虚函数动态的创建一个IDispatch接口
想知道更多的内容请在MSDN中查CreateStdDispatch
#define BEGIN_METHOD_PARAM() static  LPPARAMDATA GetParamData(LPUINT pCount) {     static  PARAMDATA   paras[] = {#define METHOD_PARAM(NAME, TYPE)    {OLESTR(#NAME), TYPE},#define END_METHOD_PARAM() {NULL, VT_EMPTY}     };     *pCount = sizeof(paras)/sizeof(paras[0])-1;     return paras; };template <class T, VARENUM TRET, int iMethod, CALLCONV cc = CC_STDCALL>
class ICallBackImpl : public IUnknown {
    typedef ICallBackImpl<T, TRET, iMethod, cc> _Myt;
    INTERFACEDATA   InterfaceData;
    METHODDATA      MethodData;
    IUnknown*       punkStdDispatch;
    LONG    ref;
    ICallBackImpl () : ref(0), punkStdDispatch(NULL) {
        UINT    count;
        InterfaceData.pmethdata = &MethodData;
        InterfaceData.cMembers = 1;
        MethodData.szName = L"";
        MethodData.ppdata = T::GetParamData(&count);
        MethodData.dispid = DISPID_VALUE;
        MethodData.iMeth = iMethod;
        MethodData.cc = cc;
        MethodData.cArgs = count;
        MethodData.wFlags = DISPATCH_METHOD;
        MethodData.vtReturn = TRET;
    }
    ~ICallBackImpl() {
        if(punkStdDispatch)
            punkStdDispatch->Release();
    }public:
    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, void** ppvObj) {
        if(riid == IID_IUnknown) {
            *ppvObj = this;
        } else if(riid == IID_IDispatch) {
            return punkStdDispatch->QueryInterface(riid, ppvObj);
        } else
            return E_NOINTERFACE;
        AddRef();        return S_OK;
    }
    ULONG STDMETHODCALLTYPE AddRef() {
        ::InterlockedIncrement(&ref);
        ods("++ %d\n", ref);
        return ref;
    }
    ULONG STDMETHODCALLTYPE Release() {
        ULONG prev = ::InterlockedDecrement(&ref);
        if(ref == 0) {
        ods("-- %d\n", 0);
            delete this;
            return 0;
        }
        ods("-- %d\n", ref);
        return ref;
    }
    static  HRESULT CreateInstance(T* pExposeObj, _Myt** pThis) {
        HRESULT hr;
        ITypeInfo* pTypeInfo;
        if(IsBadWritePtr(pThis, sizeof(*pThis)))
            return E_POINTER;
        _Myt* pobj = new _Myt();
        pobj->AddRef();
        if(pobj == NULL)
            return E_OUTOFMEMORY;
        hr = ::CreateDispTypeInfo(&pobj->InterfaceData, LOCALE_SYSTEM_DEFAULT,
 &pTypeInfo);
        if(FAILED(hr))
            goto error;
        hr = ::CreateStdDispatch(pobj, pExposeObj, pTypeInfo,
&pobj->punkStdDispatch);
        pTypeInfo->Release();
        if(FAILED(hr))
            goto error;
        *pThis = pobj;
        return S_OK;
error:
        pobj->Release();
        return hr;
    }