module Mst

  def self.included(base)
    base.extend(ClassMethods)
  end

  module ClassMethods
    def before(method_name)
      m = instance_method(method_name)
      define_method method_name do |*args, &block|
        yield
        m.bind(self).(*args, &block)
      end
    end
  end
end

class Foo
  include Mst

  def test
    puts "test"
  end

  before :test do
    puts "before"
  end
end


Foo.new.test