gistfile1.rb

module SimpleCachingTTL
  CACHETIME = 24 * 3600 # Once per day
  
  def cache(text, path)
    FileUtils.mkdir_p(File.dirname(path))
    File.open(path, 'w') { |f| f.write( text ) }
    
    text
  end
  
  def set_and_get_cache(page, render = 'erb')
    uri = request.env["REQUEST_URI"] == "/" ? 'index' : request.env["REQUEST_URI"]
    path = File.join(File.dirname(__FILE__), 'cache', "#{uri}.html")

    if File.exists?(path) && ttl?(path)
      File.open(path)
    else
      cache(send(render, page), path)
    end
  end
  
  def ttl?(path)
    File.mtime(path) + CACHETIME > Time.now
  end
end

Sinatra::Default.send :include, SimpleCachingTTL