making private methods private

private_parts.rb

# = Private Parts
#
# A little code experiment on making private methods in Ruby
# actually private.
#
# @tubbo - http://psychedeli.ca/

class PrivateParts
  def initialize
    @boobs = "( . )( . )"
    @butts = "(  )(  )"
    @balls = "( )( )"
  end

  def exposure
    peep_show
  end

  def send(method, *args)
    if private_methods.include? method
      raise NoMethodError.new("private method '#{method}' called for #{self}")
    else
      super(method, *args)
    end
  end

private
  def peep_show
    @boobs + @butts + @balls
  end
end

require 'test/unit'

class PrivatePartsTest < Test::Unit::TestCase
  def test_peep_show_cannot_be_called_outside_of_the_class
    parts = PrivateParts.new

    assert_raises(NoMethodError) { parts.peep_show }
    assert_raises(NoMethodError) { parts.send(:peep_show) }
  end

  def test_peep_show_can_be_exposed_by_exposure
    parts = PrivateParts.new

    assert_equal "( . )( . )(  )(  )( )( )", parts.exposure
  end
end

Or, if you really want that method to be private, use I Told You it Was Private (implementation). 😉