one-bit-auth_snnipet-13.rb

...

Knock::Authenticable.module_eval do
  def define_current_entity_getter(entity_class, getter_name)
    unless self.respond_to?(getter_name)
      memoization_var_name = "@_#{getter_name}"
      self.class.send(:define_method, getter_name) do
        unless instance_variable_defined?(memoization_var_name)
          current = Knock::AuthToken.new(token: token).entity_for(entity_class)

          instance_variable_set(memoization_var_name, current)
        end
        
        instance_variable_get(memoization_var_name)
      end
    end
  end
end