In Delphi you can pass class references around to compare the types of objects, and to instantiate them. Can you do the same with interface references being passed to a COM automation server?

For example, you can define a method taking a GUID parameter using the type library editor:

function ChildNodesOfType(NodeType: TGUID): IMBNode; safecall;

In this function I would like to return automation types that support the interface specified by NodeType, e.g.

if Supports(SomeNode, NodeType) then
      result := SomeNode;

But the Supports call always fails, I tried passing in the Guids defined in the type library but none of the different types (Ixxx, Class_xxxx, IId_Ixxxx) seem to work.