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IUnkown as param

PastorDwayne
PastorDwayne asked
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Last Modified: 2010-04-16
Good-day,

I need to pass IUnkown as a parameter to a function.  Here is how it is done in C++:

******************************
CComObject<CTestImpl> * m_pImpl;
m_pImpl->AddRef();
ICallBackItf * pCallBk = 0;
m_pImpl->QueryInterface(&pCallBk);
m_spInterface1->Function1(pCallBk);
******************************

What is the equivalent in C#?

Thanks for your time
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Commented:
You want to pass a callback to C# that calls into COM, is that it ?
You'll need COM interop.

In .NET you'll need the COM type definitions, and then it's just passing back a pointer and assigning it.

Have a look here:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconexposingcomcomponentstonetframework.asp?frame=true

hth

Vasco

Author

Commented:
Thanks for your response.  I followed the link, but wasn't able to find any pertinent info.  Here's more details:  I am attempting to access a COM object which has two interfaces.  I add a reference to my C# for this object; I am able to access one of the interfaces, and it's methods.  One of the method parameters is IUnknown of the second interface.  Here is what I thought might work:

**********************************
CTestImpl m_spInterface1 = new CTestImpl ();
ICallBackItf cb = m_spInterface1  as ICallBackItf;
spInterface1.(cb);
**********************************

I thought I could query spInterface1 for the IUnknown of ICallBackItf, but it doesn’t work.
Commented:
This one is on us!
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