Question

现在我终于找到了类继承如何在ruby中工作，我正在为文本RPG设计一个库存系统。然而，有一些我无法弄清楚的怪癖。

项目类：

class Item
    attr_accessor :name, :type, :attack, :armor, :wearloc, :weight, :price
    def initialize(name, type, attack, armor, wearloc, weight, price)
        @name = name
        @type = type
        @attack = attack
        @armor = armor
        @wearloc = wearloc
        @weight = weight
        @price = price
    end
end

库存类：

class Inventory
    attr_accessor :items
    def initialize
        @@items = []
    end

    def add_item(item)
        @@items << item
    end

    attr_accessor :inventory
    def inventory
        @@items.each do |item|
            puts "#{item.name} (#{item.type})"
            if item.attack != nil ; puts " %-20s %00d" % ['Attack', item.attack] ; end
            if item.armor != nil ; puts " %-20s %00d" % ['Armor', item.armor] ; end
            if item.wearloc != nil ; puts " %-20s %00s" % ['Wear', item.wearloc] ; end
            if item.weight != nil ; puts " %-20s %00d" % ['Weight', item.weight] ; end
            if item.price != nil ; puts " %-20s %00d" % ['Price', item.price] ; end
        end
    end
end

玩家类：

class Player < Inventory
    attr_accessor :playername
    def initialize(playername)
        @playername = playername
    end
end

实例化库存，创建一些项目，将它们添加到库存中都可以。

inv = Inventory.new
broadsword = Item.new('a heavy broadsword', 'weapon', 5, nil, 'wield', 15, 2)
breastplate = Item.new('a mithril breastplate', 'armor', nil, 10, 'torso', 15, 5)
ring = Item.new('a gold ring', 'armor', nil, 3, 'finger', 2, 20)
inv.add_item(broadsword)
inv.add_item(breastplate)
inv.add_item(ring)

但是，当我从Player类调用inventory方法时，我得到了所需的输出，加上3个#item对象，如下所示：

a heavy broadsword (weapon)
 Attack               5
 Wear                 wield
 Weight               15
 Price                2
a mithril breastplate (armor)
 Armor                10
 Wear                 torso
 Weight               15
 Price                5
a gold ring (armor)
 Armor                3
 Wear                 finger
 Weight               2
 Price                20
#<Item:0x007fae1b8b11d8>
#<Item:0x007fae1b8b1138>
#<Item:0x007fae1b8b1098>

为什么最后三行在那里？我无法弄清楚它的来源或解决方法。

更新

重新修改项目＆lt;库存＆lt;使用实例变量而不是类变量的播放器继承。

class Player
    attr_accessor :playername
    def initialize(playername)
        @playername = playername
    end
end

class Inventory < Player
    attr_accessor :items
    def initialize
        @items = []
    end

    def add_item(item)
        @items << item
    end

    attr_accessor :inventory
    def inventory
        @items.each do |item|
            puts "#{item.name} (#{item.type})"
            if item.attack != nil ; puts " %-20s %00d" % ['Attack', item.attack] ; end
            if item.armor != nil ; puts " %-20s %00d" % ['Armor', item.armor] ; end
            if item.wearloc != nil ; puts " %-20s %00s" % ['Wear', item.wearloc] ; end
            if item.weight != nil ; puts " %-20s %00d" % ['Weight', item.weight] ; end
            if item.price != nil ; puts " %-20s %00d" % ['Price', item.price] ; end
        end
        nil
    end
end

class Item < Inventory
    attr_accessor :name, :type, :attack, :armor, :wearloc, :weight, :price
    def initialize(name, type, attack, armor, wearloc, weight, price)
        @name = name
        @type = type
        @attack = attack
        @armor = armor
        @wearloc = wearloc
        @weight = weight
        @price = price
    end
end

inv = Inventory.new
broadsword = Item.new('a heavy broadsword', 'weapon', 5, nil, 'wield', 15, 2)
breastplate = Item.new('a mithril breastplate', 'armor', nil, 10, 'torso', 15, 5)
ring = Item.new('a gold ring', 'armor', nil, 3, 'finger', 2, 20)
inv.add_item(broadsword)
inv.add_item(breastplate)
inv.add_item(ring)

player = Player.new('Chris')
# puts player.inventory
puts inv.inventory

Answer 1

ruby中的方法返回方法中最后一个语句的值。

在Inventory#inventory的情况下，最后一个语句是@@items.each方法。 each返回调用它的集合，因此返回值为@@items数组。

如果你不想让方法返回任何东西，你可以在最后加一个零：

def inventory
  @@items.each do |item|
    # code to print the item stats
  end

  nil
end

Ruby：RPG库存系统

1 个答案: