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

class tracer
{
public:
  tracer(const std::string& name);
  ~tracer();
  template <typename T>
  tracer& operator<<(const T& t);
  std::string str();
  tracer& str(const std::string& s);
private:
  static std::ostringstream log;
  std::string name_;
};

std::ostringstream tracer::log("");

tracer::tracer(const std::string& name)
{
  log  << "\n  starting: " << (name_ = name);
}
tracer::~tracer()
{
  log << "\n  ending: " << name_;
}
template <typename T>
tracer& tracer::operator <<(const T& t)
{
  log << t;
  return *this;
}
std::string tracer::str()
{
  return log.str();
}
tracer& tracer::str(const std::string& s)
{
  log.str(s);
  return *this;
}
//----< test tracer >------------------------------------------------

void fun2(const std::string& say)
{
  tracer t("fun2");
  t << "\n    argument = " << say;
}
void fun1()
{
  tracer t("fun1");
  std::string s = "my local string";
  int count = 3;
  t << "\n    " << s << ", my count = " << count;
  fun2("hello CSE687");
}
void main()
{
  std::cout << "\n  MT3Q1b - Tracer";
  std::cout << "\n =================";
  tracer t("main");
  fun1();
  std::cout << t.str().c_str() << "\n";
  std::cout << t.str("\n  That's all Folks!\n\n").str();
}