This snippet shows how to create accessors in ruby

my_attr_accessor.rb

module Accessor
  def my_attr_accessor(*names)
    names.each do |name|
      ivar_name = "@#{name}"

      define_method(name) do
        instance_variable_get(ivar_name)
      end

      define_method("#{name}=") do |val|
        $stderr.write "changing value of #{name} to #{val}"
        instance_variable_set(ivar_name, val)
      end
    end

  end
end

class Foo
  extend Accessor

  my_attr_accessor :val, :bar
  #my_attr_accessor :bar
end

f = Foo.new
f.val = 99
puts "f's val is #{f.val}"
f.bar = 100