Butano `bn::generic_pool` basic usage

// See also https://pastebin.com/kLcr1sik

#include <bn_core.h>
#include <bn_generic_pool.h>

struct Entity {
    int x, y;
    virtual ~Entity() = default;
    Entity(int x_, int y_) : x(x_), y(y_){};
};

struct CircularBullet : public Entity {
    CircularBullet(int x_, int y_) : Entity(x_, y_){};
};
struct SquareBullet : public Entity {
    SquareBullet(int x_, int y_) : Entity(x_, y_){};
};

int main() {
    bn::core::init();
    constexpr int MaxElementSize = 64; // max size of type in bytes
    constexpr int MaxSize = 4;         // max elements count

    bn::generic_pool<MaxElementSize, MaxSize> pool;

    // Store childs as parent `Entity` type
    Entity* bullet1 = &pool.create<CircularBullet>(11, 11);
    Entity* bullet2 = &pool.create<SquareBullet>(22, 22);
    // Destory them.  don't need to know child's concrete type.
    pool.destroy(*bullet1);
    pool.destroy(*bullet2);

    while (true)
        bn::core::update();
}