Hash based SimpleHash (instead of HashWithIndifferentAccess)

simple-hash.rb

class SimpleHash < Hash
  def method_missing(method_name, *args, &block)
    if keys.map(&:to_s).include?(method_name.to_s)
      if args.empty? && block.nil?
        send(:simple_fetch, method_name)
      else
        raise "can't pass arguments and/or blocks"
      end
    else
      super
    end
  end

  def respond_to_missing?(method_name, include_private = false)
    keys.map(&:to_s).include?(method_name.to_s) || super
  end

  def methods
    super + keys
  end

  def simple_fetch(key)
    convert(fetch(key.to_sym) { fetch(key.to_s) })
  end

  private

  def convert(value)
    if value.is_a?(Hash)
      SimpleHash[value].freeze
    elsif value.is_a?(Array)
      value.map { |value| convert(value) }
    else
      value
    end
  end
end