saraid

module Refinements
  module DoFoo
    refine Object do
      def foo; :foo; end
    end
  end

  module DoBar
    refine Object do
      def bar; :bar; end

saraid

class Array
  def sum
    reduce(0) { |sum, x| sum + x }
  end
end

class Dice
  def self.roll(sides = 6)
    rand(sides) + 1
  end

saraid

class Class
  def method_invert(hash_or_existing, inverted = nil)
    hash_or_existing = Hash[[[hash_or_existing, inverted]]] unless hash_or_existing.respond_to? :each_pair
    hash_or_existing.each_pair do |existing, inverted|
      define_method(inverted) do |*args, &block|
        if self.respond_to?(existing)
          self.send(existing, *args, &block)
        else
          self.instance_variable_get(existing)
        end.!