[BlackFly]

Or in this case, since the IThingyInteractor can do exactly the same thing with an IThingy if IThingy has a name() method, you can just implement it with single dispatch.

I don't know if I have ever actually seen a true implementation of this pattern. What I have seen is a pattern someone called a Visitor where a tree is iterated over and the "Visitor" makes virtual function calls on the composite node in a single function body without ever doing something different depending on the type of the node.