Object oriented programming and interfaces

[Craig Dillabaugh]

On Monday, 4 December 2017 at 20:43:27 UTC, Dirk wrote:
> Hi!
>
> I defined an interface:
>
> interface Medoid {
>     float distance( Medoid other );
>     uint id() const @property;
> }
>
> and a class implementing that interface:
>
> class Item : Medoid {
>     float distance( Item i ) {...}
>     uint id() const @property {...}
> }
>
> The compiler says:
> Error: class Item interface function 'float distance(Medoid 
> other)' is not implemented
>
> Is there a way to implement the Item.distance() member function 
> taking any object whose class is Item?

Interfaces are expected to implement static or final functions. 
See #6 at:

https://dlang.org/spec/interface.html

interface Medoid {
     static float distance( Medoid other );
     uint id() const @property;
}


class Item : Medoid {
     static float distance( Item i ) { return 0.0f; }
     uint id() const @property { return 1; }
}