cppAgregationCompositionExample

#include <iostream>


class List
{
public:
    List() { std::cout << "List constructed\n"; }
    ~List() { std::cout << "List Destructed\n"; }
};

class Stack
{
    List* storage;
public:
    Stack() : storage{ new List } { std::cout << "Stack constructed\n"; }
    ~Stack() { delete storage;  std::cout << "Stack Destructed\n"; }
};


class Hummer
{
public:
    Hummer() { std::cout << "Hummer constructed\n"; }
    ~Hummer() { std::cout << "Hummer Destructed\n"; }
    void use() { std::cout << "Boom!\n"; }
};

class Master
{
    Hummer& tool;
public:
    Master(Hummer& h) : tool{h} { std::cout << "Master constructed with tool\n"; }
    //Master() : tool{ nullptr } { std::cout << "Master constructed without tool\n"; }
    ~Master() { std::cout << "Master Destructed\n"; }
    //void useTool() { if (tool) { tool->use(); } else { std::cout << "NO TOOLS\n"; } }
    void useTool() { tool.use(); }
};

int main()
{
    //Stack s;
    Hummer h;
    {
        Master m{h};
        m.useTool();
    }

    std::cout << "Hummer is still alive! :)\n";
    h.use();

    return 0;
}