visibility-test.rb

gistfile1.rb

class ParentClass
  def public_method
    puts '[works] parent # public'
    protected_method
  end

  protected # Can only be called from within the methods
  def protected_method
    puts '[works] parent # protected'
  end

  private
  def private_method
    puts '[works] parent # private'
  end
end

class SubClass < ParentClass
  def test_protected
    protected_method      rescue puts "[fails] subclass_instance # protected"
    self.protected_method rescue puts "[fails] subclass_instance # self.protected"
  end

  def test_private
    private_method        rescue puts "[fails] subclass_instance # private"       # implicit
    self.private_method   rescue puts "[fails] subclass_instance # self.private"  # explicit
  end
end

puts "="*40
puts "Calling from Parent Instance"
puts "="*40
parent = ParentClass.new
parent.public_method      rescue puts "[fails] parent_instance # public"
parent.protected_method   rescue puts "[fails] parent_instance # protected"

puts
puts "="*40
puts "Calling from Child Instance"
puts "="*40
child = SubClass.new
child.test_protected
child.test_private