Using namespace aliases : namespace « Language Basics « C++ Tutorial

1. C++ Tutorial
2. Language Basics
3. namespace

#include <iostream>
#include <ostream>
namespace original {
  int f();
}

namespace ns = original;     

int ns::f() { return 42; }   
using ns::f;                 

int g() { return f(); }

int main()
{
  std::cout << ns::f() << '\n';
  std::cout << original::f() << '\n';
  std::cout << g() << '\n';
}

42
42
42