method returning child, doesn't overrides declared method returning parent

[Marco Leise]

Am 29.08.2011, 22:24 Uhr, schrieb Jonathan M Davis <jmdavisProg at gmx.com>:

> It's _not_ overriding. It's implementing an interface method. Those are  
> two
> totally different things. And I think that it's horrible that Java  
> considers
> implementing an interface method as overriding it. I'd _hate_ to see  
> that in
> D.
>
> - Jonathan M Davis

This design decision in Java isn't particularly bad I think. Look at how  
dim the line is between an interface, an abstract class and a class. Some  
languages use the notion of a fully abstract class for interfaces. In case  
you implement one interface and it is somewhat internal you may choose to  
provide some default implementations and turn it into an abstract class.  
At this point you should add 'override' to the all descendant classes that  
override these implementations. If override was mandatory you could easily  
spot any methods that correspond to something higher in the hierarchy  
(extended class / interface). What would you argue for when you implement  
a method of an abstract class for example? Does it override or implement?
But D is not Java and there are already cases of implicit interfaces  
(Range). So it makes sense not to be overly verbose with interfaces in D.

- Marco