Keep getting the same value for next_seed as I get for seed.

i_dont_understand_random.rb

class RandomCollectionQueue
  def initialize(seed, collection)
    random           = ::Random.new seed
    self.collection  = collection
    self.seed        = seed
    self.next_seed   = random.rand
    self.block_index = random.rand collection.size
    p [seed, next_seed]
  end

  def dequeue
    @dequeued ||= [
      self.class.new(next_seed, collection),
      collection[block_index]
    ]
  end

  private

  attr_accessor :seed, :next_seed, :block_index, :collection
end


q = RandomCollectionQueue.new rand, [*1..10]
q, n = q.dequeue # => [#<RandomCollectionQueue:0x007fafe8b49a70 @collection=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10], @seed=0.5488135039273248, @next_seed=0.5488135039273248, @block_index=5>, 6]
q, n = q.dequeue # => [#<RandomCollectionQueue:0x007fafe8b53980 @collection=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10], @seed=0.5488135039273248, @next_seed=0.5488135039273248, @block_index=5>, 6]
q, n = q.dequeue # => [#<RandomCollectionQueue:0x007fafe8b52238 @collection=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10], @seed=0.5488135039273248, @next_seed=0.5488135039273248, @block_index=5>, 6]

# >> [0.5799812254037409, 0.5488135039273248]
# >> [0.5488135039273248, 0.5488135039273248]
# >> [0.5488135039273248, 0.5488135039273248]
# >> [0.5488135039273248, 0.5488135039273248]

Figured it out. It's a fucking type error. Kernel.rand returns a float between 0 and 1. Random#initialize must call Float#to_i on it, meaning it seeds with 0 every time.

Random.new(Random.new(Random.new(Kernel.rand  # => 0.9588543389818969
                                ).rand        # => 0.5488135039273248
                     ).rand                   # => 0.5488135039273248
          ).rand                              # => 0.5488135039273248