C++ using-declaration with enums: how to import all the enum items?

Question

Here's a code snippet to demonstrate my question.

namespace N{
    enum E { A, B, C, D };
}

int main(){
    using N::E;
    E e = A; // syntax error: 'A' is not declared
}

The last line gives me a syntax error. I'd like to use the names N::A, N::B, N::C and N::D in the main function without the namespace qualifier N::. But I don't want to do the following two things

(1) I don't want to say using namespace N, because that would import everything else in N.

(2) I don't want say using N::A, using N::B, etc for every member of the enum. Because then if I want to modify the enum, I'll have to change my main function as well. Not to mention that the extra typing is tedious and error-prone.

I tried searching for an answer myself but couldn't. Any help is appreciated.

Answer 1

If you can change the header where E is defined, try an inline namespace.

namespace N {
    inline namespace Enums {
        enum E { A, B, C, D };
    }
}

int main() {
    using namespace N::Enums;
    E e = A;
}

All the names in the inline namespace are visible in the enclosing namespace N as though the inline namespace weren't there, but this allows you to import all the names and just the names you want.