> As a user (read developer), I'd rather code to the generic interface when possible. I like that concrete implementations looks rather long and ugly
> I don't think you should be worried that your users is using direct implementations rather than the interface - their problem!
>
> Remember that in D, interfaces can contain implementations that only uses static methods on the interface:
>
> interface DB {
>     @property string name();
>     // interfaces can have implementations
>     static DB createDefault() { return new GenericDB(); }
> }
>
> class GenericDB : DB {
>     @property string name() {
>         return "generic"; }
> }
>
> class MySQLDB : DB {
>     @property string name() {
>         return "mysql"; }
> }
>
> void main() {
>     assert(DB.createDefault().name == "generic");
>     assert((new MySQLDB()).name == "mysql");
> } 

I see what you are saying.  If it is not possible to have a default I think I will call the interface Database and the class BasicDatabase as that sounds intuitive.

Thanks to everyone for the help.