// MT4Q4.cpp - what happens when?

#include <string>
#include <iostream>

class B
{
public:
  B() { 
    pStr = new std::string("default B"); 
    std::cout << "\n  B constructed";
  }
  B(const B& b) { 
    pStr = new std::string(*(b.pStr));
    std::cout << "\n  B copied";
  }
  virtual ~B() { 
    delete pStr; 
    std::cout << "\n  B destroyed";
  }
  void take(std::string str)
  {
    delete pStr;
    pStr = new std::string(str);
  }
  virtual const std::string say() { 
    return *pStr; 
  }
  B& operator=(const B& b) { 
    if(&b == this) return *this;
    delete pStr;
    pStr = new std::string(*(b.pStr)); 
    std::cout << "\n  B assigned";
  }
private:
  std::string* pStr;
};

class D : public B
{
public:
  // B has correct copy, assignment, and destruction 
  // semantics so compiler generated operations for D
  // will be correct
  virtual const std::string say() { 
    std::string temp = "from derived class: ";
    return temp + static_cast<B*>(this)->B::say(); 
  }
};

D someFunction(void)
{
  std::cout << "\n  D constructed with compiler generated D()";
  D d;
  d.take("testing someFunction()");
  std::cout << "\n  returning D instance from someFunction()";
  return d;
}

int main()
{
  B b = someFunction();

  std::cout << "\n  " << b.say() << "\n\n";
  return 0;
}