implemented GameFactory to instance an implementation of game

include/Game.h

@@ -0,0 +1,18 @@
+#pragma once
+
+class GameInternal;
+
+// TODO: add managers here
+class Game {
+public:
+    virtual ~Game() {}
+
+    virtual void init() = 0;
+    virtual void update() = 0;
+
+    GameInternal* gameInternal; //!< \deprecated  
+};
+
+
+// game factory include to simplify imports in implementation
+#include "GameFactory.h"

include/GameFactory.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include <cassert>
+#include <iostream>
+#include <map>
+#include <functional>
+#include <string>
+
+#include "Game.h"
+
+class GameInternal;
+
+class GameFactory {
+public:
+    using CreateFunc = std::function<Game*()>;
+
+    static GameFactory& instance() {
+        static GameFactory factory;
+        return factory;
+    }
+
+    void registerClass(CreateFunc createFunc) {
+        this->creator = createFunc;
+    }
+
+    Game* get() {
+        assert(this->gameInstance != nullptr);
+        return this->gameInstance;
+    }
+
+    Game* create(GameInternal* gameInternal) {
+        Game* game = this->gameInstance == nullptr ? this->creator() : this->gameInstance; // TODO: error handling
+        game->gameInternal = gameInternal;
+        this->gameInstance = game;
+        return game;
+    }
+
+    /* named game instances for future use
+    void registerClass(const std::string& className, CreateFunc createFunc) {
+        this->creators[className] = createFunc;
+    }
+
+    Game* create(const std::string& className) {
+        auto it = this->creators.find(className);
+        if (it != creators.end()) {
+            return it->second();
+        }
+        return nullptr;
+    }
+    */
+
+private:
+    CreateFunc creator;
+    Game* gameInstance = nullptr; //!< \depricated
+    // std::map<std::string, CreateFunc> creators;
+};
+
+#define REGISTER_GAME(className) \
+    static bool registered_##className = []() { \
+        GameFactory::instance().registerClass([]() -> Game* { return new className; }); \
+        return true; \
+    }();
+
+/*
+#define REGISTER_GAME(className) \
+    static bool registered_##className = []() { \
+        GameFactory::instance().registerClass(#className, []() -> Game* { return new className; }); \
+        return true; \
+    }();
+*/

include/GameInternal.h

@@ -17,13 +17,7 @@ class CollisionHandler;
 class TextureManager;
 class SoundManager;
 class Map;
-
-namespace engine {
-	extern gamefunction init;
-	extern gamefunction update;
-
-	extern GameInternal* game; // this is a temporary fix to remove artifacts of chicken_game from the engine while the API is not yet finalized
-}
+class Game;
 
 class GameInternal
 {
@@ -69,6 +63,8 @@ public:
 
 private:
 
+	Game* gameInstance;
+
 	int counter = 0;
 	bool isRunning = false;
 	SDL_Window* window;

src/GameInternal.cpp

@@ -14,8 +14,8 @@
 #include "TextureManager.h"
 #include "StatEffectsComponent.h"
 #include "Constants.h"
-
-GameInternal* engine::game = nullptr; // will be initialized in constructor
+#include "Game.h"
+#include "GameFactory.h"
 
 GameInternal::GameInternal() :
 	manager(this),
@@ -27,9 +27,7 @@ GameInternal::GameInternal() :
 	player1(manager.addEntity()),
 	player2(manager.addEntity()),
 	wall(manager.addEntity())
-{
-	engine::game = this;
-};
+{};
 
 GameInternal::~GameInternal() = default;
 
@@ -181,7 +179,8 @@ void GameInternal::init(const char* title, int xpos, int ypos, int width, int he
 	player2.addComponent<StatEffectsComponent>();
 	player2.addGroup((size_t) Entity::GroupLabel::PLAYERS);
 
-	engine::init();
+	this->gameInstance = GameFactory::instance().create(this);
+	this->gameInstance->init();
 }
 
 void GameInternal::selectCharacters(const char* &playerSprite, const char* &enemySprite)
@@ -299,7 +298,7 @@ void GameInternal::update()
 	manager.refresh();
 	manager.update();
 
-	engine::update(); // TODO: this might have to be split up into two update functions, before and after manager...
+	this->gameInstance->update(); // TODO: this might have to be split up into two update functions, before and after manager...
 }
 
 void GameInternal::render()