Marc Gregoire’s Blog

The second post in this series of C++17 features highlights a tiny but very useful new feature called nested namespaces.

Using multi-level namespaces in C++ has always been a pain. Suppose you are writing a game and you have a namespace called Core::Graphics::Rendering. Before C++17 you had to resort to something as follows

namespace Core {
    namespace Graphics {
        namespace Rendering {

            class PostProcessor
            {
            };

        }
    }
}

This leaves you with a very big indentation scheme. You could try to make it look a bit better as follows:

namespace Core { namespace Graphics { namespace Rendering {

    class PostProcessor
    {
    };

}}}

But this does not always plays nice with the auto formatting functionality of your IDE.

Say hello to C++17 nested namespaces. Now you can simply write the following:

namespace Core::Graphics::Rendering {

    class PostProcessor
    {
    };

}

Nested namespaces are supported in Microsoft Visual C++ 2015 since Update 3.