Are the Ruby instance_eval () and send () methods used to eliminate the benefits of private visibility?

Question

w = Widget.new # Create a Widget
w.send :utility_method # Invoke private method!
w.instance_eval { utility_method } # Another way to invoke it
w.instance_eval { @x } # Read instance variable of w

Looking at the example above, which refers to the Widget class (below), the send and instance_eval methods violate all the security measures provided by private and protected visibility. If so, then why bother with confidential and secure access in Ruby, since there is no guarantee that your definitions will be followed?

class Widget
  def x # Accessor method for @x
   @x
  end
  protected :x # Make it protected
  def utility_method # Define a method
   nil
  end
  private :utility_method # And make it private
end

Answer 1

If you really want to protect instances Widget, you can do this (and a bunch of other things, the code here is not a complete security solution, just indicative):

class Widget

  def some_public_method
    ...
  end

  private

  def utility_method
    ...
  end

  def send(method, *args, &block)
    raise NotImplementedError.new('Widget is secure. Stop trying to hack me.')
  end

  def instance_eval(&block)
    raise NotImplementedError.new('Widget is secure. Stop trying to hack me.')
  end

  class <<self
    private
    def class_eval(&block)
      raise NotImplementedError.new('Widget is secure. Stop trying to hack me.')
    end
  end
end

Widget.freeze

Answer 2

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Answer 3

, - rep:/.

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class Widget
  def send(method, *args, &block)
    super
  end
  #and so on
end

Ruby 1.9 : #send , __ send __ .

private Ruby : , , , API. . , - .

Answer 4

, , API- Widget.

Answer 5

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Java has a reflection. C ++ has pointers. Even Haskell has unsafePerformIO. If you want to protect your program, you need to protect it at the operating system level, without using a language.