gistfile1.rb

## reversesortby.rb
class ReverseSortBy
  include Comparable

  attr_reader :value
  def initialize(value)
    @value = value
  end

  def <=>(other)
    other.value <=> @value
  end
end

module Kernel
  def asc(value)
    value
  end

  def desc(v)
    ReverseSortBy.new(v)
  end

  module_function :asc, :desc
end



## usage
if __FILE__ == $PROGRAM_NAME then
  require 'pp'
  Person = Struct.new(:first_name, :last_name, :age)
  people = [
    Person.new('Peter', 'Pan', 23),
    Person.new('Peter', 'Pan', 15),
    Person.new('Peter', 'Parker', 15),
  ]
  pp people.sort_by { |person| [asc(person.first_name), asc(person.last_name), desc(person.age)] }
end