如何在 Ruby 类之间传递变量？

Question

我正在创建一个具有多个类别的纸牌游戏。目前，我使用全局变量来保存 $shuffled_deck、$players_hand 和 $dealers_hand 变量，但在使用全局变量时我担心（也许，不必要）并且更喜欢使用实例变量。

我一直在阅读周围的内容，但没有什么是真正令人感兴趣的。谁能帮我指出正确的方向？

使用实例变量，我无法保存 @players_hand 和 @dealers_hand 以便能够在其他类中使用它们。例如，我有来自 Player 类的 @players_hand 。我让 Dealer 类抽一张牌，但我无法将 @players_hand 拉入 Dealer 类中以将两者添加在一起。

我当前的代码是：

class Blackjack

  def initialize
    @player = Player.new
    @dealer = Dealer.new
  end
end

class Dealer

  def initialize
    @deck = Deck.new
    $dealers_hand = 0
  end

  def hit_dealer
    @deck.hit_dealer
  end

  def hit_player
    @deck.hit_player
  end

  def draw_card
    @hit = $shuffled_deck
  end

  def shuffle
    @deck.suits
  end
end

class Player

  def initialize
    $players_hand = 0
  end   
end

class Deck

 def suits
   #code that shuffled the deck..
   $shuffled_deck = @shuffled_deck
 end

 def hit_player
   @hit = $shuffled_deck.pop
 end

 def hit_dealer
   @hit = $shuffled_deck.pop
 end

end

Answer 1

使用你的例子你可以这样做

class Blackjack
  attr_reader :player, :dealer

  def initialize
    @player = Player.new
    @dealer = Dealer.new
  end
end

class Dealer
  def dealers_hand #the long java way of a getter
    @dealers_hand
  end

  #and now the short ruby way
  attr_reader :dealers_hand #if you only need to read the attribute
  attr_writer :dealers_hand #if you only need to write the attribute
  attr_accessor: dealers_hand #if you need both

  def initialize
    @deck = Deck.new
    @dealers_hand = 5
  end

  def hit_dealer
    @deck.hit_dealer
  end

  def hit_player
    @deck.hit_player
  end

  def draw_card
    @hit = $shuffled_deck
  end

  def shuffle
    @deck.suits
  end
end

class Player
  attr_reader :players_hand
  def initialize
    @players_hand = 0
  end   
end

class Deck

 def suits
   attr_reader :shuffled_deck
   @shuffled_deck = @shuffled_deck
 end

 def hit_player
   @hit = $shuffled_deck.pop
 end

 def hit_dealer
   @hit = $shuffled_deck.pop
 end

end

game = Blackjack.new
p game.dealer.dealers_hand
game.dealer.dealers_hand = 4
p game.dealer.dealers_hand

Answer 2

您想要使用 attr_reader、attr_writer 或 attr_accessor。它们的工作原理如下：

• 的值
• attr_reader :players_hand：允许您编写 some_player.players_hand 来获取该玩家的 players_hand 实例变量attr_writer :players_hand：允许您编写 some_player.players_hand = 0 将变量设置为 0
• attr_accessor :players_hand：允许您读取和写入，就像您同时使用了 attr_reader 和 attr_writer 一样。

顺便说一下，这些所做的只是为您编写方法。如果你愿意，你可以像这样手动完成：

class Player
  def initialize
    @players_hand = 0
  end  

  def players_hand
    @players_hand
  end

  def players_hand=(new_value)
    @players_hand = new_value
  end
end