單身人士和繼承C＃

Question

首先，我將說明我使用的單身人士實際上並不會在整個應用程序生命週期中。這更多的是封裝用戶所發生的事情的一種方式。

我有幾個GameState，例如InGame或MainMenu，這些函數調用非常相似，所以我想用inheritence來停止複製/粘貼。下面的代碼就是我所擁有的，但它並不像我打算的那樣工作。那就是：

BaseState.cs

abstract class BaseState 
{ 
    protected static BaseState mHandle = null; 

    protected static BaseState Handle 
    { 
     get 
     { 
      return mHandle; 
     } 
     set 
     { 
      mHandle = value; 
     } 
    } 

    public static GameState UpdateState(GameTime gameTime) 
    { 
     GameState g = GameState.MainMenu; 

     try 
     { 
      Handle.Update(gameTime); 
     } 
     catch (Exception e) 
     { 

     } 

     return g; 
    } 

    public static void DrawState(GameTime gameTime, SpriteBatch spriteBatch) 
    { 
     Handle.Draw(gameTime, spriteBatch); 
    } 

    public static void Release() 
    { 
     mHandle = null; 
    } 

    protected abstract GameState Update(GameTime gameTime); 
    protected abstract void Draw(GameTime gameTime, SpriteBatch spriteBatch); 
} 

InGame.cs

class InGame : BaseState 
{ 
    private InGame() 
    { 

    } 

    protected static new BaseState Handle 
    { 
     get 
     { 
      if (mHandle == null) 
      { 
       mHandle = new InGame(); 
      } 

      return mHandle; 
     } 
     set 
     { 
      mHandle = value; 
     } 
    } 

    protected override GameState Update(GameTime gameTime) 
    { 
     return GameState.Quit; 
    } 

    protected override void Draw(GameTime gameTime, SpriteBatch spriteBatch) 
    { 

    } 
} 

你也許可以告訴我希望能夠使用的InGame的get和set在BaseState如此我可以簡單地調用Handle.Update（），不管是從InGame還是Menu中調用它，或者不管它會知道使用哪個代碼。

顯然我需要刷新我的面向對象技能。但是，如果任何人都可以提出一種方法來讓它做我想做的事，或者提出一種不同的方式去實現它，我將不勝感激。謝謝。

Answer 1

什麼你正在努力實現並不需要一個單身，見下圖：

public abstract class BaseState 
{ 
    public GameState UpdateState(GameTime gameTime) 
    { 
     GameState g = GameState.MainMenu; 

     try 
     { 
      g = Update(gameTime); // Update returns a new state 
     } 
     catch (Exception e) 
     { 

     } 

     return g; 
    } 

    protected abstract GameState Update(GameTime gameTime); 
    protected abstract void Draw(GameTime gameTime, SpriteBatch spriteBatch); 
} 

public class InGame : BaseState 
{ 
    public InGame() 
    { 

    } 

    protected override GameState Update(GameTime gameTime) 
    { 
     return GameState.Quit; 
    } 

    protected override void Draw(GameTime gameTime, SpriteBatch spriteBatch) 
    { 
     // Draw game 
    } 
} 

public class InMenu : BaseState 
{ 
    public InMenu() 
    { 

    } 

    protected override GameState Update(GameTime gameTime) 
    { 
     return GameState.Pause; 
    } 

    protected override void Draw(GameTime gameTime, SpriteBatch spriteBatch) 
    { 
     // Draw menu 
    } 
} 

public void Foo() 
{ 
    List<BaseState> states = new List<BaseState>(); 
    states.Add(new InGame()); 
    states.Add(new InMenu()); 

    // Calls InGame.Update(...) 
    states[0].UpdateState(...); 

    // Calls InMenu.Update(...) 
    states[1].UpdateState(...); 
} 

Answer 2

那麼，你不能重載靜態成員，所以我認爲你的方法是錯誤的。你最好使用工廠或管理員類（如果需要，可以使用單例訪問當前實例），從而使您可以訪問當前的遊戲狀態。

public class GameStateManager 
{ 
    private static GameStateManager _instance = new GameStateManager(); 

    public static GameStateManager Instance { get { return _instance; } } 

    public BaseState Current { get; private set; } 

    public GameStateManager() 
    { 
     Current = new InGame(); 
    } 

    public void ChangeState(GameState state, GameTime gameTime) 
    { 
     // change your current state here, I'm not really sure about your logic here 
     Current.UpdateState(gameTime); 

     switch(state) 
     { 
      case GameState.Menu: 
       Current = new MainMenu(); 
      // etc. 
      default: 
       throw new NotImplementedException(string.Formatted("The state {0} is not implemented.", state)); 
     } 
    } 
} 

您可以使用GameStateManager.Instance訪問單身人士。