opDispatch doesn't play nice with inheritance

[Carl Sturtivant]

On Thursday, 15 November 2018 at 19:01:45 UTC, Ali Çehreli wrote:
> On 11/15/2018 09:14 AM, Carl Sturtivant wrote:
>
> > opDispatch is special in that it allows for functions to be
> added to a
> > class or struct when undefined overtly but used elsewhere but
> it seems
> > those functions sadly are final.
> >
> > Can anything useful be done to remedy the situation?
>
> For the compiler to be able to make all opDispatch 
> instantiations virtual, it would have to first see all calls 
> that generate opDispatch instantiations. (Impossible in the 
> presence of separate compilation.)
>
> Only then the compiler would know how large the vtbl of the 
> base class should be and what member functions of the derived 
> class are overrides of those virtual functions.

I suppose it's such administrative difficulties that led to D 
defining anything that might conceivably be overridden to be 
virtual, whether or not actually overridden.