# Plugin class
class Plugin
  @registered_plugins = {}

  @@trigger = ""

  def self.inherited(child)
    p child.trigger
  end

  def self.trigger
    @@trigger
  end

  def execute
    throw NotImplementedException.new
  end
end


# Some subclass of plugin class
require 'plugin'

class Foo < Plugin
  @@trigger = "!foo"

  def execute
    puts "moo"
  end
end