# File lib/mkmf.rb, line 904
def with_config(config, *defaults)
  config = config.sub(/^--with[-_]/, '')
  val = arg_config("--with-"+config) do
    if arg_config("--without-"+config)
      false
    elsif block_given?
      yield(config, *defaults)
    else
      break *defaults
    end
  end
  case val
  when "yes"
    true
  when "no"
    false
  else
    val
  end
end