An example using class instance variables

callbacks.rb

class Record
  def self.before_save(*methods)
    @callbacks ||= []
    @callbacks += methods
  end

  def self.callbacks
    @callbacks
  end

  def save
    self.class.callbacks.each do |c|
      send c if respond_to? c
    end
    puts "Saved"
  end
end

class User < Record
  before_save :saving

  def saving
    puts "Saving..."
  end
end

u = User.new
u.save

from class, this might be more readable for beginners..

send self.c if self.respond_to? c