gistfile1.rb

class Slug
  class << self
    
    def [](slug)
      redis.hget(hash, slug)
    end
    
    def []=(slug, id)
      if old = self[slug]
        redis.srem(set(old), slug)
      end
      redis.hset(hash, slug, id)
      redis.sadd(set(id), slug)
    end
    
    def destroy(id)
      redis.smembers(set(id)).each { |slug| redis.hdel(hash, slug) }
      redis.del(set(id))
    end
    
    private
    
      def redis
        $redis
      end

      def hash
        "post_ids"
      end

      def set(id)
        "post_slugs_#{id}"
      end
  end
end