ripl multi-line history plugin - two ways to easily access last edited code block

.riplrc

# Add to ~/.riplrc
module Ripl::MultiLineHistory                                                                                                                                                                                    
  attr_reader :last_buffer                                                                                                                                                                                       
                                                                                                                                                                                                                 
  # hacks multi-line's loop_once                                                                                                                                                                                 
  def loop_once                                                                                                                                                                                                  
    catch(:multiline) do                                                                                                                                                                                         
      Ripl::Shell::API.instance_method(:loop_once).bind(self).call                                                                                                                                               
      @last_buffer = @buffer && @input ? (@buffer << @input).dup : @input                                                                                                                                        
      history << @last_buffer.join('; ') if @buffer && @input                                                                                                                                                    
      @buffer = nil                                                                                                                                                                                              
    end                                                                                                                                                                                                          
  end                                                                                                                                                                                                            
                                                                                                                                                                                                                 
  require 'tempfile'                                                                                                                                                                                             
                                                                                                                                                                                                                 
  module Commands                                                                                                                                                                                                
    def last_edit(editor=ENV['EDITOR'])                                                                                                                                                                          
      t = Tempfile.new('seed')                                                                                                                                                                                   
      File.open(t.path, 'w') {|f| f.write(Array(Ripl.shell.last_buffer).join("\n")) }                                                                                                                            
      system(editor, t.path)                                                                                                                                                                                     
      Ripl.shell.loop_eval File.read(t.path)                                                                                                                                                                     
    end                                                                                                                                                                                                          
  end                                                                                                                                                                                                            
end                                                                                                                                                                                                              
Ripl::Shell.include Ripl::MultiLineHistory                                                                                                                                                                       
Ripl::Commands.include Ripl::MultiLineHistory::Commands

usage

$ ripl
>> module Cow
 > def moo
 > end
 > end
=> nil

# Press UP to edit code block as a semi-colon delimited one-liner
>> module Cow; def moo; end; end

# or use last_edit
>> last_edit
# Opens the code block in your $EDITOR.
# Code is automatically evaled upon exiting file
module Cow
def moo
end
end

=> nil

I see you've made ripper an optional engine. Looks good :)