Re: typeid of variable of interface type holding reference to derived class

[Adam D. Ruppe via Digitalmars-d-learn]

Interfaces always give their own typeid, this is because they 
might point to an object that doesn't have RTTI (though the 
compiler SHOULD be able to figure that out statically, it doesn't 
try).

To get the dynamic type, first cast it to Object, then type id.
typeid(cast(Object) o) is typeid(WhateverClass)