shouldn't override be obligatory?

[Trass3r]

> True, but using override clearly documents what you doing in that class.
> Otherwise you have to arse about looking through the interfaces to see
> if an unmarked function is an implementation, which is the same end
> result as unmarked overrides.
>
> I vote for requiring override in all cases; I think it makes things
> clearer. YMMV.
>

I guess that could be a custom annotation/attribute (if that's going to  
come sometime) so it doesn't pollute the language.