Abstract class/method in Ruby

gistfile1.rb

# These code may not be a ruby.
class AbstractKlass
  def initialize
    raise 'Abstract Class !!'
  end

  def method_a
    raise 'Called abstract method !!'
  end

  def method_b
    raise 'Called abstract method !!'
  end
end

class SubKlass < AbstractKlass
  def method_a
    puts "method_a !"
  end
end

sub_klass = SubKlass.new
sub_klass.method_a # method_a !
sub_klass.method_b # Called abstract method !! (RuntimeError)

abstract_klass = AbstractKlass.new # Abstract Class !! (RuntimeError)

SubKlass needs to overload AbstractKlass#initialize.