Re: GUID passing to managed C++

From:

"Egbert Nierop \(MVP for IIS\)" <egbert_nierop@nospam.invalid>

Newsgroups:

microsoft.public.vc.atl

Date:

Tue, 9 May 2006 09:14:37 +0200

Message-ID:

<uVDlFF0cGHA.1324@TK2MSFTNGP04.phx.gbl>

"Andrey" <andrej@telemed.lt> wrote in message
news:OWqOoSzcGHA.4900@TK2MSFTNGP02.phx.gbl...

Thank you.

Does this will work for VisualBasic, for example? It seems that
VisualBasic
uses BSTR variable to transfer GUID.

There are several simple ways to pass a GUID including a byte array
(safearray(char))

Indeed, a string is good as well in the form of
{00000306-0000-0000-C000-000000000046} for instance.

The .NET runtime (and that is not specific for visual basic) can convert all
those formats, with or without braces.

StringFromIID or StringFromGUID2 will do the trick. Pass that to the
'outside world' and it will be fine, a lot more easy than VT_RECORD ! (I
have code that works with VT_RECORD, it can pack structures but for interop
to succeed, a typelib must be available as well).

"Egbert Nierop (MVP for IIS)" <egbert_nierop@nospam.invalid> wrote in
message news:es98WSgcGHA.4700@TK2MSFTNGP02.phx.gbl...

"Andrey" <andrej@telemed.lt> wrote in message
news:OeDB7wfcGHA.1276@TK2MSFTNGP03.phx.gbl...

Hello, All.

I have implemented interface that is a connection point to my object.
One of this interface methods passes GUID as a parameter. So when
managed C++ application connects to this connection point I from my
ATL project can call this method. A problem is that managed C++
does not work correctly with GUID that is is passed via
IDispatch::Invoke
method to it. The default connection point implementation passes pointer
to GUID vairable, and this does not work. I have changed default
implementation
to send BSTR with GUID, but this does not work too. Object browser
shows that method passes "ByRef System.Guid".
The question is how to convert GUID (or reference to GUID) into the
VARIANT
to pass it with IDispatch::Invoke method correctly.

I'm afraid, the Guid data, must be packed as a VARIANT with the VT_RECORD
datatype.
And you must set the variant->pRecInfo member, the code is not simple.
(at least 20 lines of code).

If you can avoid this, try to pass a SAFARRAY(char) with size=16 bytes to
your managed C++.