Namespaces form a namespace tree in the same way that classes form a class tree. Is the class concept of inheritance valid in the namespace tree? Can I inherite properties from class which declared above in a namespaces hierarchy ?
The question isn't very clear. I'll assume you're talking about VisualWorks namespaces. There's no significance to the parent-child relationship in that hierarchy. So if you have a class in Foo and a class in Foo.Bar they don't automatically see each other. But a class Foo.Bar.Subclass can certainly inherit from Foo.ParentClass. Or the other way around.