Called by the framework when Excel opens the XLL
virtual void OnXllOpen( );
This function is called whenever a user loads the add-in, whether using the Excel Tools - Add-ins dialog or directly, using the File - Open menu option.
This is a good time to do any initialization that needs to precede any use of your add-in functions, so long as the initialization cannot fail.
The default implementation of this function does nothing.
This method is deprecated. Use OnXllOpenEx instead.