[tutorial] Commend pattern

#include <iostream>
#include <vector>
#include <functional>


class Recipes
{
public:
    static void brewCoffee() { std::cout << "dripping Coffee through filter\n"; }
    static void brewTea() { std::cout << "steeping Tea\n"; }

    static int amountWaterMl(int ml) { return ml; }

};

class CaffeineBeverage
{
public:
    CaffeineBeverage(std::function<int()> amountWaterMl, std::function<void()> brew)
        : _amountWaterMl(amountWaterMl)
        , _brew(brew)
    {}

    void prepare() {
        boilWater(_amountWaterMl());
        _brew();
        pourInCup();
    }

private:
    void boilWater(int ml) { std::cout << "boiling " << ml << " water\n"; }
    void pourInCup() { std::cout << "pour in cup\n"; }
    std::function<int()> _amountWaterMl;
    std::function<void()> _brew;
};

class CoffeeMachine
{
public:
    typedef std::vector<std::function<void()>> OrderQ;
    OrderQ orders;

    CoffeeMachine()
        : orders()
    {}

    void request(OrderQ::value_type order)
    {
        orders.push_back(order);
    }

    void start()
    {
        for (auto const& order : orders) { order(); }
        orders.clear();
    }
};

int main()
{
    CoffeeMachine coffeeMachine;
    CaffeineBeverage coffee([] { return Recipes::amountWaterMl(150); }, &Recipes::brewCoffee);
    CaffeineBeverage tea([] { return Recipes::amountWaterMl(200); }, &Recipes::brewTea);

    coffeeMachine.request([&] { coffee.prepare(); });
    coffeeMachine.request([&] { tea.prepare(); });
    coffeeMachine.start();

    return 0;
}