template <class ProductType>
class ConcreteCreator : public Creator {
public:
    ConcreteCreator();
    virtual Product* MakeProduct() override;
};

template <typename Type, typename... Args>
class Singleton;
using MyClassSingleton = Singleton<MyClass, int, int>;
MyClassSingleton::Instance(800, 600);

class Adapter : public Target, private Adaptee

Facade& Facade::Instance() noexcept {
    static Facade instance;
    return instance;
}

template <class Item>
class ConcreteAggregate : public Aggregate<Item> {
public:
    // ...
    void        Push(Item item) noexcept;
    void        Pop() noexcept;
    Item        Top() const;
    // ...
private:
    std::array<Item, MAX_CAPACITY> m_data;
};

class Colleague {
public:
    virtual void Changed();
    virtual void ConnectTo(Mediator* mediator);
    // ...
};