Grouping posts by month concept

posts.rb

require 'date'

class Month
  attr_accessor :year, :month

  def initialize(year, month)
    self.year = year
    self.month = month
  end

  def to_s
    Date.new(year, month).strftime('%B, %Y')
  end

  def hash
    [year, month].hash
  end

  def eql?(other)
    other.year == year && other.month == month
  end
end

class Post
  def month
    Month.new(2011, 10)
  end
end

posts = [Post.new, Post.new, Post.new]
puts posts.group_by(&:month).inspect
# => { October, 2011=>[#<Post:0x007ff7418ca2b8>, #<Post:0x007ff7418ca290>, #<Post:0x007ff7418ca268>] }