Differing implementations for a function in two interfaces

[BCS]

In article <e1s7gd$r15$1 at digitaldaemon.com>, BCS says...
>
>In article <e1s2sr$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. 
[...]

Oops:

I forgot to state my position

The problem I stated before is conceptually vary easy to solve: somehow,
explicitly set the contents of the vtbls used by C when cast to I or J. The
solution that you proposed, while workable, is a vary poor design. It is
wasteful in runtime, program size, memory usage, code size and maintenance cost.