Ruby: RPG库存系统

Question

现在我终于知道了类继承在ruby中是如何工作的，我正在为文本rpg设计一个库存系统。不过，有些怪癖我还是搞不明白。

物品类别：

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

库存类别：

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

球员班：

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

实例化库存，创建几个项目，并将它们添加到清单中所有工作。

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，以及3 #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>

为什么最后三条线在那里？我不知道它是从哪里来的，也不知道怎么解决它。

更新：

用实例vars而不是类vars重新处理项< Inventory < Player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

方法返回方法中最后一条语句的值。

对于Inventory#inventory，最后一条语句是@@items.each方法。each返回它被调用的集合，因此返回值是@@items数组。

如果不希望该方法返回任何内容，则可以将0放在末尾：

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

  nil
end