floppy.rb

class Floppy
  def method_missing(method, *args)
    super unless args.length > 0 && method.to_s[-1..-1] == "="
   
    if args.first.is_a?(Proc)
      (class << self; self; end).class_eval do  
        define_method(method.to_s[0..-2].to_sym, args.first)  
      end  
    else
      (class << self; self; end).send(:attr_accessor, method.to_s[0...-1])
      send(method, args.first)
    end
  end  
end

require 'test/unit'

class FloppyTest < Test::Unit::TestCase
  
  def setup
    @foo = Floppy.new
  end
  
  def test_assign_proc_adds_method
    @foo.bar = lambda { "bar" }
    assert_equal "bar", @foo.bar
  end
  
  def test_assign_object_add_attr
    @foo.name = "Foo"
    assert_equal "Foo", @foo.name
  end
  
  def test_method_method_still_works
    assert_raise NoMethodError do
      @foo.alakazam
    end
  end
  
end