private-is-too-public.rb

class A
  public
  def do_thing(x)
    super_secret_internal_implementation_function_xpjdljadhlhjjalj(x) * 10
  end
  
  private
  # randomly chosen name no one else is likely to use:
  def super_secret_internal_implementation_function_xpjdljadhlhjjalj(x)
    x*x
  end
end

class B < A
  # other implementation omitted...

  private
  # randomly chosen name no one else is likely to use:
  def super_secret_internal_implementation_function_xpjdljadhlhjjalj(x)
    "Oh Noes!"
  end
end  

=begin
 
    dm@red:~$ irb
    2.3.0 :001 > load 'private-is-too-public.rb'
     => true 
    2.3.0 :002 > A.new.do_thing 4
     => 160 
    2.3.0 :003 > B.new.do_thing 4
     => "Oh Noes!Oh Noes!Oh Noes!Oh Noes!Oh Noes!Oh Noes!Oh Noes!Oh Noes!Oh Noes!Oh Noes!" 

Dammit, I wanted 160.

Workaround: all methods you want truly unclobberable by your
descendents need to be prefixed by the classname. This is admittedly
ugly but given the alternative between bugs and ugliness, one has to
choose ugliness.

=end