gistfile1.rb

#!/usr/bin/ruby

require "rubygems"
require "yaml"

class Model
  def initialize(file)
    @file  = file
    @_attr = YAML::load_file(@file) || {}
  end

  def save
    File.open(@file, 'w') do |out|
      YAML::dump(@_attr, out)
    end
  end

  private
  def self.vattr(*keys)
    keys.each do |key|
      define_method(key) { @_attr[key] }
      define_method("#{key}=") { |val| @_attr[key] = val }
    end
  end
end
 
class User < Model
  vattr :id, :login
end


user = User.new('user.yaml')

user.login = 'demo'
user.id = 1
user.save

demo = User.new('user.yaml')
puts demo.login