metakoans_training/knowledge/koan_09_1o.rb

class SomeClass
end

# NOTE: This is the original koan_09_1.rb but has a regression failure.
# The current koan_09_1.rb, and koan_09_2.rb show another way to inline
# method definitions.
class Module
  def attribute(params='a', &block)
    name, default_value = process_args(params)

    value = default_value
    attribute_assigned = false

    define_method(name) do
      unless value
        if attribute_assigned or block.nil?
          nil
        else
          instance_eval &block
        end
      else
        value
      end
    end
    define_method(name + "?") { !send(name).nil? }
    define_method(name + "=") { |new_value| value = new_value; attribute_assigned = true }
  end

  private

  def process_args(params)
    name = nil
    default_value = nil
    if params.is_a?(Hash)
      name = params.keys[0]
      default_value = params[name]
    else
      name = params
    end

    [name, default_value]
  end

end