Re: Using the VB/VBA Collection class in C++ code

"Alexander Nickolov" <>
Tue, 22 Aug 2006 09:32:24 -0700
You need to call IDispatch::Invoke with DISPID_NEWENUM (-4)
and you get a VARIANT with VT_UNKNOWN as a result.
QI that IUnknown pointer for IEnumVARIANT and off
you go...

_NewEnum (the usual name for the hidden DISPID_NEWENUM
property) is a read-only property defined on all collection

Alexander Nickolov
Microsoft MVP [VC], MCSD

"Rob Perkins" <finitedev@community.nospam> wrote in message

Gary Chang[MSFT] wrote:

Hi Rob,

Does anyone have pointers to some documentation
or books (preferably something in O'Reilly's Safari collection, but I'm
not picky) which could guide me on how to define the get_ and put_

I am not familar with the O'Reilly's Safari books, but I found some code
samples and atricles on how to implement a VBA like collection in ATL:

Safari is not an imprint of O'Reilly's. It's their online library of
books, which includes several imprints, but sadly none of the Microsoft
Press books.

Even so, I don't want to *create* a VBA-like collection in ATL. I want to
*use* a VBA.Collection object created in VB6 and set as a property in my
ATL object. Presumably that means I take a reference passed in by my VB6
application, and either copy

CComPtr<VBA::Collection> ptr = pVal //?

or QI

CComPtr<VBA::Collection> ptr;
pVal->QueryInterface(IID_theIIDoftheVBACollectionClass, &ptr); //?

...the reference to store my pointer internally in my ATL/COM object.

I can't remember whether VB6 will addref the object when it calls out to
an inproc DLL or not (I'm thinking not). I suppose I could pass the
pointer "as Object" and QI in any case, but I still need to know where and
how to get at the methods of the VBA Collection class once the object is
marshalled in and I have a reference.

So... still lost, because I'm not trying to duplicate Collection
functionality for myself, I'm trying to use an object created for me by
VB6 inside my ATL8 class.

And naturally, I can't resist snarking a bit, that if the
VFW/DirectShow/Windows Media people had written managed interfaces for
their stuff in all the years .NET has been around, this wouldn't even be a


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