using symbols from a namespace in one function but not another in the same file

Question

I have to define two functions, say, foo() and bar() in the same namespace and the same file. For the definition of the first, foo(), I want to use all symbols of, say, namespace other, but don't want symbols from namespace other to be automatically in scope for my other function, bar(). Is this possible? How?

(note: I don't want to know about alternative "solutions" either avoiding this problem of mitigating it, such as namespace o=other etc.)

Answer 1

Yes, it is possible:

void foo()
{
  using namespace abc;
  ....
}

or

void foo()
{
  using abc::x;
  using abc::y;
  using abc::z;
  ....
}

Answer 2

#include <iostream>
void quux() { std::cout << "root\n"; }

namespace other {
  void quux(int x = 0) { std::cout << "other\n"; }
}
namespace taxes {
  void foo() {
    using namespace other;
    quux(3);
  };

  void bar() {
    quux();
  }
}

int main() {
  taxes::foo();
  taxes::bar();
}

Live example

Note that quux in bar would be ambiguous if it could see other::quux, but it cannot.

On the other hand, this does not give you access to namespace other in the 'head' of the function foo (the parameters etc), but that is a rare requirement. There might be a solution involving inline namespaces or the like, but probably not worth the confusion.