[Mingw-users] About COM vtable Generation

[Hilary C. <hil...@us...>]

Hi All,

    I am trying implements a COM Object though C++ class. It means I 
create a new C++ Instance
and pass the this object to the Microsoft COM Object. But I found that 
there is a bug (?) of mingw32
for the generation of vtable.

class  __attribute__((com_interface)) IHelloWorld : public 
IOleClientSite, IDispatch

    I have implemented all the interface of the IOleClientSite, 
IDispatch, IUnknown. IDispatch and IUnknown
is fine. It has no problems for the Microsoft COM Object to call the 
IDispatch and IUnknown Methods. But
for the IOleClientSite interface, Microsoft COM Object throws a 
exception that indicated there is a null pointer
to the IOleClientSite. I have tried to generate the assembly files 
thought gcc. It has generated the vtable and
function pointer of IDispatch and IUnknown. But there is no Function 
Implementation of IOleClientSite. If I add
one more interface implementation of to my classes, like the following

class  __attribute__((com_interface)) IHelloWorld : public 
IServiceProvider, IOleClientSite, IDispatch

    It has generated the IOleClientSite function implementations. But No 
IServiceProvider function implementations.
It is STRANGE! or am I miss sths during COM implementation ? ( I know 
that mingw32 has not got the full COM
implementation.)

Regards,

Hilary