c++ - Forward declaring classes in namespaces -

I was surprised to know that I could not move a square forward to any other radius using the scope resolution operator Increase, i.e.

  class someScope :: someClass;  

Instead, the full declaration is to be used as follows:

  Namespace {class someClass; }  

Does anyone say that this is the matter?

UPDATE: To clarify, I why is the case.

You can not declare a class outside your namespace, because compiler some scope < Do not be aware of the type of / strong>.

Namesh place {} must declare the existence of Nameshoot, and then, declare class some class in its realm