# File lib/em/pure_ruby.rb, line 448
    def initialize io
      @uuid = UuidGenerator.generate
      @io = io
      @last_activity = Reactor.instance.current_loop_time

      if defined?(Fcntl::F_GETFL)
        m = @io.fcntl(Fcntl::F_GETFL, 0)
        @io.fcntl(Fcntl::F_SETFL, Fcntl::O_NONBLOCK | m)
      else
        # Windows doesn't define F_GETFL.
        # It's not very reliable about setting descriptors nonblocking either.
        begin
          s = Socket.for_fd(@io.fileno)
          s.fcntl( Fcntl::F_SETFL, Fcntl::O_NONBLOCK )
        rescue Errno::EINVAL, Errno::EBADF
          warn "Serious error: unable to set descriptor non-blocking"
        end
      end
      # TODO, should set CLOEXEC on Unix?

      @close_scheduled = false
      @close_requested = false

      se = self; @io.instance_eval { @my_selectable = se }
      Reactor.instance.add_selectable @io
    end