snippet.rb

class Box
  def options(h={})
    @options ||= self.class.options.merge(h)
  end
  
  def self.options(h={})
    @class_options ||= h
  end
  
  def self.define_defaults(ops={})
    puts "# defining #{self} defaults: #{ops.inspect} - "
    ops.each do |k, v|
       self.options[k.to_sym] = v
      methods_to_define = {
       # :class_attr => "class << self; @#{k}=#{v}; def #{k}; @#{k}; end; end",
       :class_get => "class << self; def #{k}; self.options[:#{k}]; end; end",
       :instance_get_and_set => "def #{k}(i=nil); i ? options[:#{k}] = i : options[:#{k}]; end",
       :instance_set_with_eql => "def #{k}=(v);options[:#{k}]=v;end"
      }
      methods_to_define.each {|method, definition| 
        puts definition
        class_eval definition
      }
    end
  end
  
end

defaults = {:open => false, :color=>'brown', :optioddns=>'optional'}
Box.define_defaults(defaults)
p Box.options
p Box.open # == false
p Box.color #=='brown'

puts "-- should be all true --"
p Box.open == false
p Box.color =='brown'
b=Box.new
p b.open == false
p b.color == 'brown'
b.color= 'red'
p b.color == 'red'
puts '-- done --'

p b.inspect
p Box.options

p Box.public_methods(false)
p b.public_methods(false)