Polymorphic call through non-virtual method

Polymorphic call through non-virtual method

I have a little problem with polymorphism. My simple code:


Animal.h
class Animal {
public:
Animal();
Animal(const Animal& orig);
virtual ~Animal();
virtual void get();
};

Animal.cpp
#include "Animal.h"
#include <iostream>
using namespace std;
Animal::Animal() {
cout << "Animal is born" << endl;
}
void Animal::get() {
cout << "get() from an Animal!" << endl;
}


Bird.h
class Bird : public Animal {
public:
Bird();
Bird(const Bird& orig);
virtual ~Bird();
void get();
};

Bird.cpp
#include "Bird.h"
#include <iostream>
using namespace std;
Bird::Bird() {
cout << "Bird is born" << endl;
}
void Bird::get() {
cout << "get() from a Bird!" << endl;
}


Chicken.h
#include "Bird.h"
class Chicken : public Bird {
public:
Chicken();
Chicken(const Chicken& orig);
virtual ~Chicken();
void get();
};

Chicken.cpp
#include "Chicken.h"
#include <iostream>
using namespace std;
Chicken::Chicken() {
cout << "Chicken is born" << endl;
}
void Chicken::get() {
cout << "get() from a Chicken!" << endl;
}



There is also a factory method returning an Animal* pointer to the
concrete implementation based on input:

Factory.h
#include "Animal.h"
#include "Bird.h"
class Factory {
public:
Factory();
Factory(const Factory& orig);
virtual ~Factory();
Animal* generateAnimal();
Bird* generateBird();
};

Factory.cpp
#include "Factory.h"
#include "Animal.h"
#include "Bird.h"
#include "Chicken.h"
#include <iostream>
#include <string>
#include <stdlib.h>
using namespace std;
Animal* Factory::generateAnimal() {
string choice;
cout << "What do you want? 1-Animal, 2-Bird, 3-Chicken" << endl;
cin >> choice;
Animal* animal;
if (choice.at(0) == '1') {
cout << "You chose Animal" << endl;
animal = new Animal();
return animal;
} else if (choice.at(0) == '2') {
cout << "You chose Bird" << endl;
animal = new Bird();
return animal;
} else if (choice.at(0) == '3') {
cout << "You chose Chicken" << endl;
animal = new Chicken();
return animal;
} else {
cout << "Wrong input" << endl;
exit(1);
}
}
Bird* Factory::generateBird() {
string choice;
cout << "What do you want? 1-Animal, 2-Bird, 3-Chicken" << endl;
cin >> choice;
Bird* bird;
if (choice.at(0) == '2') {
cout << "You chose Bird" << endl;
bird = new Bird();
return bird;
} else if (choice.at(0) == '3') {
cout << "You chose Chicken" << endl;
bird = new Chicken();
return bird;
} else {
cout << "Wrong input" << endl;
exit(1);
}
}


I omitted ctors & dtors.
main.cpp
#include <cstdlib>
#include <iostream>
#include "Factory.h"
#include "Animal.h"
#include "Bird.h"
#include "Chicken.h"
using namespace std;
int main(int argc, char** argv) {
Factory factory;
Animal* animal = factory.generateAnimal();
animal->get();
return 0;
}



The concrete implementation of an Animal class is resolved during runtime.
It's obvious, that removing the virtual keyword from Animal class results
in calling Animal implementation of get() method, whether animal* points
to Bird or Chicken.
What do you want? 1-Animal, 2-Bird, 3-Chicken
3
You chose Chicken
Animal is born
Bird is born
Chicken is born
get() from an Animal!
It's also obvious, that calling the virtual get() method results in
polymorphic call to the concrete subclass. What concerns me is this
situation: Instead of
Animal* animal = factory.generateAnimal();
animal->get();
we have
Bird* bird = factory.generateBird();
bird->get();
We have a pointer to Bird class, in which the get() method is NOT virtual.
The output is:
What do you want? 1-Animal, 2-Bird, 3-Chicken
3
You chose Chicken
Animal is born
Bird is born
Chicken is born
get() from a Chicken!


How does it happen, that call to non-virtual function results in virtual
call to the subclass? Is "virtualism" inherited? If it is, is it somehow
possible to perform a non-virtual call to the pointer class, instead of
implementation class?