// File: ex7-12.cpp

// This example shows that "virtualness" is passed down to derived classes

// even if the immediate "parent" class does not name a function as virtual.

// It also illustrates polymorphism implemented through references instead

// of pointers to base objects.


#include <iostream>
#include <string>
using namespace std;

class person
{
  public:
	 virtual string who_am_i() const { return "person"; }
	 string non_virtual_who_am_i() const { return "non_virtual person"; }
};

class child : public person
{
  public:
	 string who_am_i() const { return "child"; }
	 string non_virtual_who_am_i() const { return "non_virtual child"; }
};
class grand_child : public child
{
  public:
	 string who_am_i() const { return "grand_child"; }
	 string non_virtual_who_am_i() const { return "non_virtual grand_child"; }
};

void identify_yourself(const person& p)
{
  cout << "I am a " << (p.who_am_i()) << endl;
  cout << "I am a " << (p.non_virtual_who_am_i()) << endl;
}

int main()
{
  person P;
  child C;
  grand_child G;
  person* pp;
  pp = &P;
  cout << (pp->who_am_i()) << endl;
  cout << (pp->non_virtual_who_am_i()) << endl;
  pp = &C;
  cout << (pp->who_am_i()) << endl;
  cout << (pp->non_virtual_who_am_i()) << endl;
  pp = &G;
  cout << (pp->who_am_i()) << endl;
  cout << (pp->non_virtual_who_am_i()) << endl;
  cout << "sizeof(person) = " << sizeof(person) << endl;
  cout << "sizeof(child) = " << sizeof(child) << endl;
  cout << "sizeof(grand_child) = " << sizeof(grand_child) << endl;
  identify_yourself(P);
  identify_yourself(C);
  identify_yourself(G);
}