CODE:

class Scene
{
public:
	virtual ~Scene(){}
	///<summary>Called when this instance is selected as the current scene.</summary>
	virtual void OnSelectedAsCurrent( IGameContext &Context ) = 0;

	///<returns>Whether a redraw is required. (If returns true, <see cref="Paint"/> will be called.)</returns>
	///<remarks>
	///If this method calls IGameContext::TransToXXXScene() method and returns true,
	///Paint() of other instance correspond to the target scene will be called (rather than of this instance).
	///</remarks>
	virtual bool Update( IGameContext &Context, const Input_b &rInput, RndGenerator &Rnd ) = 0;
	
	//
	virtual void Paint( HDC hdc, const IGameContext &Context ) const = 0;
};

CODE:

enum class DifficultyLV { Normal, Hard };

//Scene側から，ゲームの全体的な状況に対して何かするのに必要な処理手段を提供する
class IGameContext
{
public:
	virtual ~IGameContext(){}
public:
	virtual void TransToTitleScene() = 0;
	virtual void TransToGamePlayScene( DifficultyLV GameLV ) = 0;
public:
	///<returns>
	///Returns the difficulty that selected as argument to <see cref="TransToGamePlayScene"/>
	///</returns>
	virtual DifficultyLV GetCurrentGameLV() const = 0;

	///<returns>
	///This method always returns the same value.
	///(left, top) is (0,0), and (width, height) is paintable range size.
	///</returns>
	virtual const RECT &ViewRect() const = 0;
};

CODE:

void 管理側具体実装::TransToTileScene()
{//「カレントのシーン」を「タイトルシーン」にすげ替える最もシンプルな実装ってこんな感じだよねきっと
  delete m_pCurrentScene;  //おおっと！
  m_pCurrentScene = new TitleScene();
}

CODE:

ChangeSceneTo( std::unique_ptr<Scene> &Tgt );  //引数の適切な型がわからんけど