扁平化作用域

gistfile1.rb

class CleanRoom
  def run(setups, &block)
    setups.each do |setup|
      instance_eval &setup
    end
    instance_eval &block
  end
end

def init
  events ||= {}
  setups ||= []

  Kernel.send :define_method, :event do |name, &block|
    events[name] = block
  end

  Kernel.send :define_method, :setup do |&block|
    setups << block
  end

  Kernel.send :define_method, :each_event do |&block|
    events.each do |name, event|
      CleanRoom.new.run(setups) do
        block.call name, event
      end
    end
  end

end

init

setup do
  puts "Setting up sky"
  @sky_height = 260
end

setup do
  puts "Setting up mountaints"
  @mountains_height = 200
end

event 'the sky is falling' do
  @sky_height < 300
end

event "it's getting closer" do
  @sky_height < @mountains_height
end

each_event do |name, event|
    puts name if self.instance_eval(&event)
end