struct TextureManager final
{
	Texture& Get(...);
};

struct AudioManager final
{
	Sound& Get(...);
};

struct Game;

class GlobalResources final
{
public:
	static TextureManager& GetTextureManager() {return *this->textureManager;}
	static AudioManager& GetAudioManager() {return *this->audioManager;}
	static Game& GetGameInstance() {return *this->gameInstance;}

	static void ProvideTextureManager(TextureManager& manager);
	// ...

private:
	static TextureManager* textureManager;
	static AudioManager* audioManager;
	static Game* gameInstance;
};

struct Game final
{
	TextureManager textureManager;
	AudioManager audioManager;

	Game()
	{
		GlobalResources::ProvideTextureManager(this->textureManager);
		GlobalResources::ProvideAudioManager(this->audioManager);
		GlobalResources::ProvideGameInstance(*this);
	}
};