99 Bottles of Beer

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# 99 Bottles of beer, in Ruby
# By Victor Borja, Sep 14, 2006
# This one shows my favorite Ruby features:
#   continuations, open classes, singleton classes, blocks and being funny!

class Integer # The bottles
  def drink; self - 1; end
end

class << song = nil
  attr_accessor :wall

  def bottles
    (@bottles.zero? ? "no more" : @bottles).to_s <<
      " bottle" << ("s" unless @bottles == 1).to_s
  end
  
  def of(bottles)
    @bottles = bottles
    (class << self; self; end).module_eval do
      define_method(:buy) { bottles }
    end
    self
  end
  
  def sing(&step)
    puts "#{bottles.capitalize} of beer on the wall, #{bottles} of beer."
    if @bottles.zero?
      print "Go to the store buy some more, "
      step = method :buy
    else
      print "Take one down and pass it around, "
    end
    @bottles = step[@bottles]
    puts "#{bottles} of beer on the wall."
    puts "" or wall.call unless step.kind_of? Method
  end

end

callcc { |song.wall| song.of(99) }.sing { |beer| beer.drink }

Alternative Versions

Version	Author	Date	Comments	Rate
object-oriented version	Mike Gertz	04/20/05	2
In words	Daniel Straight	07/10/06	1
shows inheritance, iterators, yield, etc	Kian Wright	06/10/05	0
Readably re-opening Integer, teetotaller	Eric Budd	01/06/08	0
wall-based OO version	Kevin Baird	07/07/05	2
alternative version	Greg T.	05/18/05	10
minimal version	Anonymous	05/18/05	3
monkeypatch and anonymous procs	J. B. Rainsberger	04/04/07	0

Comments

 I like Ruby said on 01/13/07 01:31:44

This may not be the shortest and most efficent version, but it's defenitly the version with the most fun reading it.
Especialy the parts "wall.call" if you need the next bottle, "step = method :buy" if you have no beer left and "beer.drink" as what to do in each stanza.

I would actualy call it a geek poem.

For those of you who don't code Ruby: Learn Ruby, so you can enjoy reading this poem and writing your next scripts/applications/whatever.

 Pepe said on 01/19/07 20:33:48

Yeah men, keep doing the good work. How Deep is this men, it moves me to tears.

 rafa said on 01/25/07 18:49:34

I really like this over the other versions, I think it shows more the ruby way.

The part I liked the more was the last line, especially "}.sing {", that makes use of a not commonly known behavior of ruby continuations. When the continuation is called the first time, the #sing message is sent to the value resulting from the body of callcc, however subsequent calls to the continuation (by means of wall.call) always send the #sing message to the nil object. I proved this by changing "song = nil" to "song = Object.new", now I understand why Victor used nil as the song, a very cleaver choice !.

 Hesenrre said on 01/26/07 02:05:15

Jejejejeje, like your coding friend :D, ruby rules!!!!

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