如何在Ruby類之間傳遞變量？

Question

我正在創建一個有多個班級的紙牌遊戲。目前，我使用全局變量來保存$shuffled_deck,$players_hand和$dealers_hand變量，但是我擔心使用全局變量（可能是不必要的）並且更願意使用實例變量。

我一直在閱讀，但沒有什麼是真正的點擊。任何人都可以幫助我指出正確的方向嗎？

使用實例變量我無法保存@players_hand和@dealers_hand以便能夠在其他類中使用它們。例如，我有Player類的@players_hand。我有Dealer類拉牌，但我不能將@players_hand拉到Dealer類將兩者加在一起。

我當前的代碼是：

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

你想用attr_reader，attr_writer，或者attr_accessor。下面是它們的工作原理：

• attr_reader :players_hand：允許你寫some_player.players_hand來獲取玩家的players_hand實例變量
• attr_writer :players_hand的價值：讓你寫some_player.players_hand = 0的變量設置爲0
• attr_accessor :players_hand：允許你既可以讀寫，也可以使用attr_reader和attr_writer。

順便提一句，所有這些都是爲您寫的方法。如果你願意，你可以手工做這樣的：

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 

Answer 2

使用您的例子中，你可以做這樣的

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