Differing implementations for a function in two interfaces

[BCS]

In article <e1s2sr$n4s$1 at digitaldaemon.com>, Hasan Aljudy says...
>
>What you want is exactly what polymorphism is designed for. I really 
>don't understand what's your problem.
>
I don't believe that D can solve the following problem. I can see several way to
get a _similar_ effect but all have substantial penalties involving code
complexity, speed or maintainability/extensibility

If you can use you suggested approach to solve this problem I would be pleased
to see it.
---------------
You are given this (you may not modify it)

interface I {int get();}
interface J {int get();}

1) You need to make a class C that implements both I and J that has different
action for I.get and J.get.

2) Classes derived from C must be able to override the action of both I.get and
Jget

3) Given an instance, c, of the class C, the following statements must work.
I i = c;
i.get	// must call the appropriate I.get even if c is of a derived type.
J j = c
j.get	// must call the appropriate J.get even if c is of a derived type.

4) Converting a C object to an I or J interface must not rely on the overloading
of the cast operation (e.i. "I i = c;" must not call any methods)

5) Must be simply extendable to interfaces with lots of function (one more
function in I must not require more than one function be defined to keep C up to
date)

I believe these requirements for a programming solution to be vary reasonable.
If I were working in a programming shop and assigned a subordinate to the
problem as defined through point 2, I would expect that 3-5 would be assumed.