event monitoring system - example for scope, blocks, procs, lambdas in ruby source: metaprogramming-ruby

own_dsl.rb

lambda {
  setups = []
  events = {}
  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_pair do |name, event|
      block.call name, event
    end 
  end

  Kernel.send :define_method, :each_setup do |&block| 
    setups.each do |setup|
      block.call setup
    end 
  end

}.call

Dir.glob('*events.rb').each do |file| load file
  each_event do |name, event|
    env = Object.new each_setup do |setup|
      env.instance_eval &setup
    end
    puts "ALERT: #{name}" if env.instance_eval &event 
  end
end