"The last feature": overridable methods in interfaces

[Trass3r]

> I only see two differences with abstract classes: interfaces can't have  
> instance (and class?) variables and you can inherit from multiple  
> interfaces. Am I missing something? Is this really necessary? Isn't  
> abstract classes enough? Does this have similar problems (or the same)  
> as multiple inheritance?
>
>

Yeah, providing default functionality that can be overridden is exactly  
what abstract classes are for.
Interfaces were introduced to circumvent all those multiple inheritance  
problems!