gistfile1.rb

#app/models/document.rb
class Document < ActiveRecord::Base
  
  has_attached_file :attachment, styles: {html: {}}, :processors => [:htmlprocessor]

  attr_accessor :attachment_file_name
 
end


#lib/paperclip_processors/htmlprocessor.rb
module Paperclip
  class Htmlprocessor < Processor
    
    class InstanceNotGiven < ArgumentError; end

    def initialize(file, options = {})
      super
      @file = file
      @instance = options[:instance]
      @current_format   = File.extname(@file.path)
      @basename         = File.basename(@file.path, @current_format)
    end
    
    def make
      @file.pos = 0 # Reset the file position incase it is coming out of a another processor      
      dst = Tempfile.new([@basename, "html"].compact.join("."))
      Paperclip.run("#{RAILS_ROOT}/DocumentConverter.py", "#{File.expand_path(@file.path)} #{File.expand_path(dst.path)}")
      dst
    end
    
  end
end