passing duck-typed objects and retaining full type information

[Adam Taylor via Digitalmars-d-learn]

> Not entirly sure of what you asking for,but have you tried
> inhertance?
> ----
> interface Base(C){
>      /+...+/
> }
>
> interface Derived(C):Base!C{
>      /+...+/
> }
> ----

No, i'm specifically looking for a solution that is NOT 
inheritance based.  I've been looking at solutions based on 
opDispatch or template mixins -- but so far haven't come up with 
anything.