// PersistStream.cpp

#include <iostream>
#include <sstream>
#include <fstream>
#include <string>

/////////////////////////////////////////////////////////////
// Required solution starts here
//
class PersistStream
{
public:
  PersistStream();
  PersistStream(const std::string& filename, const std::string& msg);
  ~PersistStream();
  template <typename T>
  PersistStream& operator<<(const T& t);
  std::string say();
private:
  static std::ofstream out;
};

std::ofstream PersistStream::out;

PersistStream::PersistStream()
{
  if(!out.good())
    throw exception("\n  stream not attached to file\n\n");
}

PersistStream::PersistStream(
  const std::string& filename, const std::string &msg)
{
  out.open(filename.c_str());
  if(!out.good())
    throw exception("\n  can't open file");
  out << msg;
}

PersistStream::~PersistStream()
{
  // don't close stream out, since it is static;
}

template <typename T>
PersistStream& PersistStream::operator<<(const T& t)
{
  out << t; 
  return *this;
}
// Required solution ends here
/////////////////////////////////////////////////////////////

std::string PersistStream::say()
{
  out.close();
  std::ostringstream temp;
  std::ifstream in("temp.tmp");
  temp << in.rdbuf();
  return temp.str();
}

void localStream()
{
  PersistStream ps("temp.tmp","Log File - temp.dat");
  ps << "\n  data from function localStream()";
}

void main()
{
  try
  {
    localStream();
    PersistStream ps;
    ps << "\n  A line from main";
    ps << "\n  a double from main: " << 3.1415927 << "\n\n";
    std::cout << ps.say();
  }
  catch(std::exception& e)
  {
    std::cout << "\n  " << e.what() << "\n\n";
  }
}