Does your Range exclude end? Make it a surprise!

range_with_indeterminate_exclusion.rb

require 'fiddle'

class RangeWithIndeterminateExclusion < Range
  def initialize min, max
    pointer = Fiddle::Pointer.new Fiddle.dlwrap self

    Thread.new do
      loop do
        sleep rand
        pointer[Fiddle::SIZEOF_LONG * 4] ^= true.object_id
      end
    end

    super
  end
end

range = RangeWithIndeterminateExclusion.new 1, 10
#=> 1..10

range
#=> 1...10

range
#=> 1..10