system.h

#pragma once
 
#include <SFML/System/Time.hpp>
#include <SFML/Window/Event.hpp>
 
namespace core
{
class SystemInterface
{
public:
    virtual ~SystemInterface() = default;
    virtual void Begin() = 0;
    virtual void Update(sf::Time dt) = 0;
    virtual void End() = 0;
};
 
class OnEventInterface
{
public:
    virtual ~OnEventInterface() = default;
    virtual void OnEvent(const sf::Event& event) = 0;
};
 
}