round_to.rb

module RoundTo
    # def self.included(klass)
    #   if klass.instance_method(:round)
    #     klass.class_eval do
    #       begin
    #         remove_method :round
    #       rescue NameError
    #       end
    #     end
    #     super
    #   else
    #     raise NoMethodError, 'no round method found'
    #   end
    # end
  
  # A more versitile rounding function that rounds to an arbitrary number
  # of decimil places
  def round_to(places = 0)
    unless Integer === places
      raise TypeError, "argument places has to be an Integer"
    end
    if places < 0
      max_places = -Math.log(self.abs + 1) / Math.log(10)
      raise ArgumentError, "places has to be >= #{max_places.ceil}" if max_places > places 
    end
    t = self
    f = 10.0 ** places
    t *= f
    if t >= 0.0
      t = (t + 0.5).floor
    elsif t < 0.0
      t = (t - 0.5).ceil
    end
    t /= f
    t.nan? ? self : t
  end
end

class ::Float # :nodoc:
  unless method_defined?(:round_to)
    include RoundTo
  end
end