reaction.rb

class Reaction
  def initialize(yield_to)
    self.yield_to = yield_to
  end

  def method_missing(method_name, *)
    if yieldable?(method_name)
      yield if block_given?
    end
  end

  def respond_to_missing(*)
    true
  end

  def ==(other)
    self.yield_to == other.yield_to
  end

  def yieldable?(method_name)
    yield_to == method_name
  end

  private
  attr_accessor :yield_to

  protected :yield_to
end