Is there a better way to express nested namespaces in C++ within the header

Question

I switched from C++ to Java and C# and think the usage of namespaces/packages is much better there (well structured). Then I came back to C++ and tried to use namespaces the

Answer 1

C++ namespaces are used to group interfaces, not to divide components or express political division.

The standard goes out of its way to forbid Java-like use of namespaces. For example, namespace aliases provide a way to easily use deeply-nested or long namespace names.

namespace a {
namespace b {
namespace c {}
}
}

namespace nsc = a::b::c;

But namespace nsc {} would then be an error, because a namespace may only be defined using its original-namespace-name. Essentially the standard makes things easy for the user of such a library but hard for the implementer. This discourages people from writing such things but mitigates the effects if they do.

You should have one namespace per interface defined by a set of related classes and functions. Internal or optional sub-interfaces might go into nested namespaces. But more than two levels deep should be a very serious red flag.

Consider using underscore characters and identifier prefixes where the :: operator isn't needed.