require 'open-uri'require 'time'require 'rexml/document'# Example:## flickr = Flickr.new('http://www.flickr.com/services/feeds/photos_public.gne?id=40235412@N00&format=rss_200')# flickr.pics.each do |pic|#   puts "#{pic.title} @ #{pic.link} updated at #{pic.date}"# end#class FlickrAggregation  include REXML  def choose(num)    return pics unless pics.size > num    bag = []    set = pics.dup    num.times {|x| bag << set.delete_at(rand(set.size))}    bag  end  attr_accessor :url, :pics, :link, :title, :description  # This object holds given information of a picture  class Picture    attr_accessor :link, :title, :date, :description    def to_s      title    end    def date=(value)      @date = Time.parse(value)    end    def image      description.scan( /(http:\/\/(farm1|farm2|static|photos).*?\.jpg)/ ).first.first     end    def thumb      image.gsub( /\_m\./, '_t.' )    end    def square      image.gsub( /\_m\./, '_s.' )    end  end  # Pass the url to the RSS feed you would like to keep tabs on  # by default this will request the rss from the server right away and  # fill the tasks array  def initialize(url, refresh = true)    self.pics  = []    self.url    = url    self.refresh if refresh  end  # This method lets you refresh the tasks int the tasks array  # useful if you keep the object cached in memory and  def refresh    open(@url) do |http|      parse(http.read)    end  endprivate  def parse(body)    xml = Document.new(body)    self.pics        = []    self.link         = XPath.match(xml, "//channel/link/text()").to_s    self.title        = XPath.match(xml, "//channel/title/text()").to_s    self.description  = XPath.match(xml, "//channel/description/text()").to_s    XPath.each(xml, "//item/") do |elem|      picture = Picture.new      picture.title       = XPath.match(elem, "title/text()").to_s      picture.date        = XPath.match(elem, "pubDate/text()").to_s      picture.link        = XPath.match(elem, "link/text()").to_s      picture.description = XPath.match(elem, "description/text()").to_s      pics << picture    end  endend