COM - 如何创建一个返回指向接口的指针的方法？

Question

如何在COM中创建一个返回指向接口的指针的方法,这需要在IDL文件中完成.

编辑:

我如何在一个类中实现它:

STDMETHODIMP CBlah::get_Something(IOtherBlah** retval){
return m_protectedvar->QueryInterface(retval);
}
STDMETHODIMP CBlah::put_Somthing(IOtherBlah* rhs){
m_protectedvar = rhs;
return S_OK;
}

以上不起作用.我收到以下错误:

cannot instantiate abstract class with[ Base=Blah ] due to following members:
'HRESULT IBlah::putref_Something(IOtherBlah*)' : is abstract

Answer 1

像这样的东西:

 interface IYourInterface {
     HRESULT GetPointer( [out, retval]IInterface** );
 };

来电者会这样称呼它:

 IInterface* pointer = 0;
 HRESULT hr = yourInterfacePointer->GetPointer( &pointer );