(10) Chengye defeat also Sho Ho? Iunknowex

Related UML:


Look at the code for a query interface:
//////////////////////////////////////////////////////////////////////////

Interface Query macros
#define QueryInterface (Interface,guid,dwqueryver) \
if ((guid==iid_# #Interface) && (Interfaceversioncheck (dwqueryver,ver_# #Interface)) \
Return to Static_cast<interface *> (this);

#define QUERYINTERFACE_IUNKNOWNEX (baseinterface,guid,dwqueryver) \
if ((Guid==iid_iunknownex) && (Interfaceversioncheck (Dwqueryver,ver_iunknownex)) \
Return Static_cast<iunknownex *> (Static_cast<baseinterface *>);

Get interface macros
#define GET_MYSELF_INTERFACE (INTERFACE) \
((Interface *) QueryInterface (iid_# #Interface, ver_# #Interface))

#define GET_OBJECT_INTERFACE (object,interface) \
((Interface *) object.queryinterface (iid_# #Interface, ver_# #Interface))

#define GET_OBJECTPTR_INTERFACE (pobject,interface) \
((pobject==null)? NULL: ((Interface *) pobject->queryinterface (iid_# #Interface, ver_# #Interface)))

//////////////////////////////////////////////////////////////////////////


Interface Query
void * __cdecl ceventservice::queryinterface (const IID & Guid, DWORD dwqueryver)
{
QueryInterface (Ieventservice,guid,dwqueryver);
Queryinterface_iunknownex (Ieventservice,guid,dwqueryver);
return NULL;
}

Because of the existence of this function, the interface passes the type check from the compile time to the runtime.
The delivery of any interface only needs to pass a Iunknowex pointer, and then the receiver uses IUNKNOWEX to determine whether it is the interface it needs.
This mechanism is good or bad, it's hard to say,