passing VB object reference to COM

[wglass]

Hi,

I have a COM object that generates an object for a VB app, which stores it and then passes it back to the COM object for further manipulation. I can generate it fine, but can't figure out how to pass a VB "object" back to COM. Specifically I keep getting Access Violations when I call QueryInterface.

VB CODE:

Set obj = Engine.getObject    ' works fine
EngineFactory.saveObject obj  ' doesn't work

Engine.getObject returns a VT_DISPATCH pointer to a custom IForioObject.

C++ CODE:

STDMETHODIMP CEngine::saveObject(BSTR *PathName, IDispatch *Model, VARIANT_BOOL *ReturnVal)

IForioObject *ForioObj;
HRESULT hr = Model->QueryInterface(IID_IForioObject, (void**)&ForioObj);

On this last line, my C code always crashes with a access violation. It appears that the VB code is not passing in the original object.

Any ideas out there? Help is appreciated.

Best, WILL

 

[vishnuprasad]

EngineFactory object should support the object being passed for further processing, i.e your QueryInterface is not returning a valid reference back.