From: David Alan Black <dblack@...>
Date: 2001-08-04T21:50:23+09:00
Subject: [ruby-talk:19129] Re: My 1st look @ ruby: No prototypes and problem with String#gsub

Hello --

On Sat, 4 Aug 2001, Stefan Scholl wrote:

> class Shuffle
> 	def initialize(data)
> 		raise(TypeError, "not an array") if data.type != Array
> 		@store = data
> 		@mark = Array.new
> 		@marked = 0
> 	end
>
> 	def each
> 		while @marked < @store.length
> 			while @mark[i = rand(@store.length)]
> 			end
> 			@mark[i] = true
> 			@marked += 1
> 			yield @store[i].gsub(/ /, '\\ ')
> 		end
> 	end
> end
>
> Shuffle.new(ARGV).each {|s| print "#{s} " }


This seems like a lot of code to write, and variables to use, to get
this to happen.  Also, I don't think Shuffle makes for a very good
class.  Shuffling is a more method-like concept.  It's also a general
enough thing that you could make a case for adding it directly to
class Array.  It might be handy to have a "bang" (modify in place)
version and a non-bang version:

   class Array
     def my_shuffle!
       size.times do
	 push slice! rand(size)
       end
       self
     end

     def my_shuffle
       dup.my_shuffle!
     end
   end

   ARGV.my_shuffle.each do |e|
     print e.gsub(/ /, '\\\\\&') + " "
   end


(Maybe some mathematician could check this for correctness :-) It
actually runs pretty fast for non-huge arrays, if I'm remembering some
old benchmark results correctly.)


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav