C++ - namespace

gistfile1.cpp

using namespace foo; //generic, the same behaviour in Java, include com.foo.*

using bar;// specific, the same behaviour in Java, include com.package.bar;

gistfile2.cpp

void function_test(std::string a, std::function<void (const string&)> original_function{
  
  std::sting b = create_random_string();
  
  return [b, original_function](const string_t& c)
  {
      if (validate(b, c))
      {
          original_function(c);
          
      }

  }
}