Variants

In Delphi, VarDispProc points to a routine that is called to execute methods (or access properties) of an interface that is assigned to a System::Variant. The Variants unit assigns a procedure that generates error 222 or raises an EVariantDispatchError exception. The ComObj unit reassigns this variable to a procedure that generates the appropriate COM IDispatch calls.  

To control how Variants execute methods when they have a value that is an interface, assign your own procedure to VarDispProc.  

EVariantDispatchError