C++ Alias Declaration scope


Example

Alias Declaration are affected by preceding using statements

namespace boost
{
    namespace multiprecision
    {
        class Number ...
    }
}


using namespace boost;

//   Both Namespace are equivalent 
namespace Name1 = boost::multiprecision;
namespace Name2 = multiprecision;

However, it is easier to get confused over which namespace you are aliasing when you have something like this:

namespace boost
{
    namespace multiprecision
    {
        class Number ...
    }
}

namespace numeric
{
    namespace multiprecision
    {
        class Number ...
    }
}

using namespace numeric;
using namespace boost;

//    Not recommended as 
//    its not explicitly clear whether Name1 refers to
//    numeric::multiprecision or boost::multiprecision
namespace Name1 = multiprecision;

//    For clarity, its recommended to use absolute paths
//    instead
namespace Name2 = numeric::multiprecision;
namespace Name3 = boost::multiprecision;