Smart Pointers

shared_ptr_inheritance_test.cpp

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

class MusicProduct {
public:
	MusicProduct() {}
	virtual void play() const = 0;
	virtual void displayTitle() const = 0;
};

class Cassette : public MusicProduct {
public:
	Cassette() {}
	virtual void play() const { cout << "Play a cassette." << endl; }
	virtual void displayTitle() const { cout << "Display a cassette." << endl; }
};

class CD : public MusicProduct {
public:
	CD() {}
	virtual void play() const { cout << "Play a CD." << endl; }
	virtual void displayTitle() const { cout << "Display a CD." << endl; }
};

class Bluelay {
public:
	Bluelay() {}
	virtual void play() const { cout << "Play a Bluelay." << endl; }
	virtual void displayTitle() const { cout << "Display a Bluelay." << endl; }
};

void displayAndPlay(const shared_ptr<MusicProduct>& pmp, int numTimes) {
	for ( int i = 1; i <= numTimes; ++ i )
	{
		pmp.get()->displayTitle();
		pmp.get()->play();
	}
}


int main() {
    auto funMusic = std::make_shared<Cassette>();
    auto nightmareMusic = std::make_shared<CD>();
    auto playstation4 = std::make_shared<Bluelay>();
	
	auto anotherFunMusic = funMusic;
	
	displayAndPlay( funMusic, 10 );
	displayAndPlay( nightmareMusic, 0);
	// displayAndPlay( playstation4, 0);    // compile error
	
	cout << funMusic.use_count() << endl;
	cout << anotherFunMusic.use_count() << endl;
}