class Listen::Options

def initialize(opts, defaults)
  @options = {}
  given_options = opts.dup
  defaults.each_key do |key|
    @options[key] = given_options.delete(key) || defaults[key]
  end
  given_options.empty? or raise ArgumentError, "Unknown options: #{given_options.inspect}"
end

def method_missing(name, *_)
  respond_to_missing?(name) or raise NameError, "Bad option: #{name.inspect} (valid:#{@options.keys.inspect})"
  @options[name]
end

def respond_to_missing?(name, *_)
  @options.has_key?(name)
end