Sizes - Use ruby's comparable to compare clothe's sizes (XS, S, M, L, XL, etc)

size.rb

class Size
  include Comparable

  def initialize(str)
    unless ALL_STRS.include? str
      raise ArgumentError, "#{str} is not a valid size"
    end

    @str = str
  end

  attr :str

  def self.[](str)
    find(str)
  end

  def self.find(str)
    all.find { |size| size.str == str } or raise ArgumentError, "#{str} is not a valid size"
  end

  def self.all
    Size::ALL
  end

  def succ
    ALL[ALL_STRS.index(str) + 1]
  end

  def <=>(other)
    ALL_STRS.index(self.str) <=> ALL_STRS.index(other.str)
  end

  def inspect
    %|#<Size "#{str}">|
  end

  ALL_STRS = %w(XXS XS S M L XL XXL 3XL 4XL 5XL 6XL 7XL)
  ALL = ALL_STRS.map { |str| Size.new(str) }
end

p Size::ALL
# => [#<Size "XXS">, #<Size "XS">, #<Size "S">, #<Size "M">, #<Size "L">, #<Size "XL">, #<Size "XXL">, #<Size "3XL">, #<Size "4XL">, #<Size "5XL">, #<Size "6XL">, #<Size "7XL">]

p (Size['XS']..Size['XXL']).to_a
# => [#<Size "XS">, #<Size "S">, #<Size "M">, #<Size "L">, #<Size "XL">, #<Size "XXL">]

p Size['XS'] > Size['XL']
# => false