Declaring Private Methods on on a Specific Instance of a Class in Ruby

gistfile1.rb

class Person
  def name
    nickname? ? 'Bob' : 'Robert'
  end

  def nickname?
    false
  end
end

bob = Person.new

# This doesn't throw an exception because public
bob.nickname?

bob.instance_eval do
  def nickname?
    true
  end
end

class << bob
  private :nickname?
end

# This throws an exception because private
bob.nickname?

jim = Person.new

# This doesn't throw an exception because public.  The privacy was only for that instance's nickname? method
jim.nickname?