Private vs. Protected in Ruby

protected.rb

class Foo

  protected

  def protected_method
    puts "protected method"
  end

  private

  def private_method
    puts "private method"
  end

end

class Bar < Foo

  def call_protected_method
    protected_method
  end

  def call_private_method
    private_method
  end

  def call_protected_method_with_self
    self.protected_method
  end

  def call_private_method_with_self
    self.private_method
  end

end

# Bar.new.protected_method # => NoMethodError: protected method ‘protected_method’ called for #<Bar:0x1022bb968>
# Bar.new.private_method # => NoMethodError: private method ‘private_method’ called for #<Bar:0x1022bb968>

Bar.new.call_protected_method # => "protected method"
Bar.new.call_private_method # => "private method"

Bar.new.call_protected_method_with_self # => "protected method"
# Bar.new.call_private_method_with_self # => NoMethodError: private method ‘private_method’ called for #<Bar:0x1022bb0f8>