/////////////////////////////////////////////////////////////////////
// shared.cpp - Solution of MT#3-Q4                                //
//                                                                 //
// This is a demo showing how to make the required declarations    //
// It provides no useful functionality.  Main does nothing useful. //
/////////////////////////////////////////////////////////////////////

template <typename T>
class shared
{
public:
  static T& value();
private:
  static T _value;
};

template <typename T>
T shared<T>::_value;

template <typename T>
T& shared<T>::value()
{
  // do something here to control access
  //   if access is not allowed you can throw an exception
  //   or return a static dummy value of type T
  return _value;
}

#include <iostream>
using namespace std;

void someFunction()
{
  shared<double> sd;
  // use the shared value
  cout << "\n  getting shared value = " << sd.value();
}

int main()
{
  shared<double> sd;
  cout << "\n  setting shared value to " << (sd.value() = 2.5);
  someFunction();
  cout << "\n\n";
}