/*
 * This code is written all in one file for instructional simplicity only; you should always split
 * your code into separate header files
 */
#include<list>
#include<iostream>
using namespace std;
class Animal {
    public:
        virtual void describe() = 0;
        bool isAlive();
        Animal(bool isAlive);
        virtual ~Animal();
    private:
        bool isAlive_;
};
class Monkey : public Animal {
    public:
        void describe();
        Monkey();
        ~Monkey();
};
class Parrot : public Animal {
    public:
        void describe();
        Parrot();
        ~Parrot();
};
Animal::Animal(bool isAlive) : isAlive_(isAlive) {}
Animal::~Animal() {
    cout << "cleaning cage" << endl;
}
bool Animal::isAlive() { return isAlive_; }
/* Note that another way we could have fixed this would be to add a default
 * constructor for Animal.  The downside to that solution is that if the default
 * didn't do the right initialization, the compiler wouldn't issue a warning
 * and something would likely go wrong at runtime.  So if you're inheriting
 * from a class with a default constructor, it's best to just get in the habit
 * of always explicitly calling the base class constructor, even if it's the
 * default. */
Monkey::Monkey() : Animal(true) {}
Monkey::~Monkey() {
    cout << "releasing tree branches" << endl;
}
void Monkey::describe() {
    cout << "A monkey!" << endl;
}
Parrot::Parrot() : Animal(true){}
Parrot::~Parrot() {
    cout << "Flying away" << endl;
}
void Parrot::describe() {
    cout << "A many-colored parrot" << endl;
}


int main() {
    list<Animal*> l;
    l.push_back(new Monkey());
    l.push_back(new Parrot());
    list<Animal*>::iterator it;
    for (it = l.begin(); it != l.end(); it++) {
        (*it)->describe();
        cout << "This animal is alive: " << (*it)->isAlive() << endl;
	delete (*it);
    }
    return 0;
}