// This code illustrates the use of a factory method
// to hide the details of subclasses from the user.
// Note random use of override & final for teaching purposes.

#include <iostream>
#include <string>

using namespace std;

class Dog {
  public:
    static Dog *create(double weight, const string &name);  // Factory method
    Dog(const string &n) : name(n) {}
    virtual ~Dog() = default;
    string who() const { return name; }
    virtual string bark() const = 0;
    virtual string breed() const = 0;
  private:
    const string name;			// MUST use member initialization.
};

class Chihuahua : public Dog {
  public:
    Chihuahua(const string &n) : Dog(n) {}
    ~Chihuahua() {}
    string bark() const { return "¡yip!"; }
    string breed() const { return "Chihuahua"; }
};

class Beagle : public Dog {
  public:
    Beagle(const string &n) : Dog(n) {}
    ~Beagle() = default;
    string bark() const override { return "bow wow"; }
    string breed() const final { return "beagle"; }
};

class GreatDane : public Dog {
  public:
    GreatDane(const string &n) : Dog(n) {}
    ~GreatDane() = default;
    string bark() const override final { return "WOOF‼‼"; }
    string breed() const { return "Great Dane"; }
};


// Factory method!
Dog *Dog::create(double weight, const string &name) {
    if (weight < 10) return new Chihuahua(name);
    if (weight > 80) return new GreatDane(name);
    return new Beagle(name);
}

// No user code, below, mentions any class but Dog.
// If we were to add more cases to Dog::Create(), we wouldn’t
// need to recompile main().

int main() {
    Dog *a = Dog::create(4, "Ren");
    Dog *b = Dog::create(15, "Snoopy");
    const Dog *c = Dog::create(120, "Scooby-Doo");
    cout << a->who() << " the " << a->breed() << " says " << a->bark() << '\n'
	 << b->who() << " the " << b->breed() << " says " << b->bark() << '\n'
	 << c->who() << " the " << c->breed() << " says " << c->bark() << '\n';
    delete a;
    delete b;
    delete c;
}