sample_instance_eval.rb

class X
  def do_something
    '**PUBLIC**'
  end
  
  private
  
  def do_something_privately
    '--private--'
  end
end


> x = X.new
> x.do_something             # => **PUBLIC**
> x.do_something_privately   # => NoMethodError: private method do_something_privately
> x.instance_eval { do_something_privately }   # => --private--