I've had to set up a new interface pointer with initial values (particularly
where the object being created has a parent-child type relationship), but I
don't recall ever using a dynamic cast. A typical piece of code looks like
this:

HRESULT RiskWorldDB::AddConnection(LPCSTR dsn, LPCSTR user, LPCSTR password,
        IDispatch ** pRiskWorldConnection)
{
        CComObject<RiskWorldConnection> *con = NULL;
        HRESULT hr = CComObject<RiskWorldConnection>::CreateInstance(&con);

        if (SUCCEEDED(hr))
        {
                hr = con->QueryInterface (IID_IDispatch, reinterpret_cast<void
**>(pRiskWorldConnection));
                if (FAILED(hr))
                        delete con;
                else
                {
                        con->Init(this);
                        con->m_dsn = dsn;
                        con->m_user = user;
                        con->m_password = password;
                        m_connections.push_back(con);
                }
        }
        return hr;
}

Does that help?

Hugh
http://www.iwebthereforeiam.com/TaborMap.asp
The largest collection of Tim Tabor resource links in the charted universe

-----Original Message-----
From: Distributed COM-Based Code [mailto:DCOMDISCUSS.MICROSOFT.COM]On
Behalf Of Ben Callister
Sent: Monday, July 23, 2001 4:58 PM
To: DCOMDISCUSS.MICROSOFT.COM
Subject: Question: No RTTI Data when registering VC COM component under
CO M+...

Hi All:

i have a COM component created with VC++. this component contains the
TSession COM class. this class has a method as part of the *C++* structure
of the class (not part of the COM interface) - TSession::SetName(string
sName). whenever i CoCreateInstance() on this class from inside C++, i
perform a dynamic_cast<TSession*>(pSession) to get to the C++ portion of the
class structure so that i can call the SetName() method before handing the
actual ITSession interface pointer back to the client. this is for
initialization purposes. this works fine and the component runs great when
it is registered normally via the system registry. however, when i register
this component under COM+ via the catalog, the component throws an exception
when i perform the actual dynamic_cast call. the error i get is:

'Access Violation - No RTTI Data!'
 -2147467259 (80004005)

i have 'Enable RTTI...' turned ON in the project settings. does anyone know
why i am having this problem? and why this occurs only when registered under
COM+? any answers, comments, suggestions, etc are greatly appreciated.

thanks,

Benjamin Callister
Vice President of Engineering
Tutor.com
Real Tutors. Real Results.

e: bcallistertutor.com
p: 212.528.3101; x.227
w: http://www.tutor.com <http://www.tutor.com/>

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