Question

class Warcraft 

  def initialize &block
    instance_eval &block
  end

  def method_missing name, *args, &block
    instance_variable_set("@#{name}".to_sym, args[0])
    self.class.send(:define_method, name, proc { instance_variable_get("@#{name}")})
  end

  def game &block
    @game = Game.new &block
  end

  class Game 
    def initialize &block
      instance_eval &block
    end

    def method_missing name, *args, &block
      instance_variable_set("@#{name}".to_sym, args[0])
      self.class.send(:define_method, name, proc { instance_variable_get("@#{name}")})
    end   
  end

end

warcraft = Warcraft.new do
  name "Warcraft III"
  battle_net :iccup

  game do
    side :sentinels
    hero "Furion"
    rune_appear_every 2
  end
end

puts warcraft.inspect # => #<Warcraft:0x00000000be3e80 @name="Warcraft III", @battle_net=:iccup, @game=#<Warcraft::Game:0x000000009c6c38 @side=:sentinels, @hero="Furion", @rune_appear_every=2>>

如何访问嵌套方法？

puts warcraft.battle_net # => iccup
puts warcraft.side #=> #<Proc:0x000000010de6d8@dsl.rb:9 (lambda)>
puts warcraft.game #=> dsl.rb:18:in `instance_eval': block not supplied (ArgumentError)
puts warcraft.game.side #=> dsl.rb:18:in `instance_eval': block not supplied (ArgumentError)

Answer 1

puts warcraft.game会抛出错误，因为您的Warcraft#game方法需要一个块，并且您将其称为属性访问器。

我不确定你在这里需要什么，但是如果你想使用Warcraft#game方法获得当前游戏以及设置新游戏那么你可以返回当前游戏没有给出一个块，如下所示：

def game &block
  if block_given?
    @game = Game.new &block
  else
    @game
  end
end

DSL时访问嵌套方法

1 个答案: