Virtual methods

[Trass3r]

> Let's try again. I think there can be two types of opaque binary only  
> modules:
> - Ones compiled from C code, or with a C interface. Such modules can't  
> contain classes, so there is no problem with virtual functions.
> - Ones compiled from D code, or that use the D code interface, that can  
> contain and use classes and virtual calls. The language can require such  
> modules to contain a data structure that tells the compiler what's safe  
> to do.
>

What about C++ code?