Ruby NullObject pattern

null_object.rb

# see http://devblog.avdi.org/2011/05/30/null-objects-and-falsiness/
class NullObject
  def to_a; []; end
  def to_s; ""; end
  def to_f; 0.0; end
  def to_i; 0; end
  def tap; self; end
  def nil?; true; end
  def present?; false; end
  def empty?; true; end
  # def !; true; end
  def method_missing(*args, &block)
    self
  end
end
# def Maybe(value)
#   case value
#   when nil then NullObject.new
#   else value
#   end
# end
# # We could try another tack. We could define a function to “resolve” the null object back to a nil when needed#k:
# def Value(object)
#   case object
#   when NullObject then nil
#   else object
#   end
# end