From: ptkwt@...1.aracnet.com (Phil Tomson)
Date: 2003-01-21T12:55:13+09:00
Subject: redefining rand and srand


A couple of questions:
1) how good is Ruby's rand function (what's the quality of randomness)?  I 
suspec that it is just the same as C's rand, so there won't be a 
difference.
2) I'd like to plug in my own random number generator that would probably 
produce higher-quality random numbers than the current rand does.  I'm 
pretty sure it should be doable and easy, like:

module Kernel
  def rand(max=0)
    #do random number generation magic here
  end
end

But what about overriding srand(num)?  srand seeds the random number 
generator, so I'm assuming there is some module variable that gets set by 
srand and which rand uses as well... So I figure the way to do it is 
something like:

module Kernel
  def rand(max=0)
    generate_random(@seed)
  end
  def srand(seed=nil)
    if not seed
      #generate @seed using combiation of time, process id and sequence#
    else
      @seed = seed
    end
  end
end

....however I'm guessing that I wouldn't have to redefine srand if I could 
find the name of the module variable being used.  I tried @seed, but it 
wasn't it.... Kernel.instance_variables didn't help either.

Phil
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