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

From:
"Alexander Nickolov" <agnickolov@mvps.org>
Newsgroups:
microsoft.public.vc.atl
Date:
Mon, 28 Aug 2006 09:06:17 -0700
Message-ID:
<#Y0OmvryGHA.1824@TK2MSFTNGP03.phx.gbl>
First off, you are supposed to simply store a copy of the
original collection in your putref method. That aside, your
bug is using DISPATCH_METHOD instead of DISPATCH_PROPERTYGET.
As I already mentioned, this is a read-only property, not
a method. BTW, you are not checking the return value of
Invoke. If you pass a value for the EXCEPINFO structure,
you may get detailed error information too (for debugging
purposes, no point doing it in a release build...).

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================

"Rob Perkins" <finitedev@community.nospam> wrote in message
news:4l9n0nFtt2mU1@individual.net...

Alexander Nickolov wrote:

Ah, you simply accept IDispatch* as the property type.
My explanation was how you use the collection, accepting
it is trivial...


Not so trivial.

My code in VB reads:

   Dim c As New Collection
'fill collection here ...

   Dim m As New ClassWithIDispatchProperty
   Set m.FilesCollection = c

...where FilesCollection is the IDispatch property. putref_ looks like
this:

STDMETHODIMP ClassWithIDispatchProperty::putref_FilesCollection(IDispatch*
newVal)
{
   // TODO: Add your implementation code here

   unsigned int * puArgErr = 0;
   VARIANT result;
   VariantInit(&result);
   newVal->Invoke(-4,
                  IID_NULL,

(LCID)MAKELCID(MAKELANGID(LANG_NEUTRAL,SUBLANG_NEUTRAL), SORT_DEFAULT),
                  DISPATCH_METHOD,
                  NULL,
                  &result,
                  NULL,
                  puArgErr);
   if (result.vt==VT_UNKNOWN) {
       if (FAILED(result.punkVal->QueryInterface(IID_IEnumVARIANT,(void
**) &m_FilesCollection)))
           return E_INVALIDARG;
   } else {
       return E_INVALIDARG;
   }
   return S_OK;
}

I've passed in a collection with 200 IPictureDisp's in it, but the result
of that Invoke() is a vt of "Empty"

Ideas?

Rob

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