Is there a reason to use a 100% abstract class and not an interface ?
Can you give me a good example when to use both so I can grasp the concept a little?
Update:
100% Abstract class -> abstract class with only abstract methods.
I’m curios if there are differences between php and java regarding this aspect.
Update2:
Even if I understand most of the reasons I’m more interested in the conceptual more than technical reasons.
If by “100% abstract class” you mean “abstract class with no concrete methods”, then I can think of a reason: visibility.
You can define an abstract method to be protected, and hence not part of the public API of the class. However, that seems like an odd design.
Another thing that came to my mind is when you expect to add common functionality to the base class – i.e. if it is likely to have some utility methods shared by all implementors, but these methods are not implemented.
Another thing – instance variables. You can have inheritable instance variables in the abstract class.