如何使用 AnyEvent 监听读取和写入事件？

Question

   $w = AnyEvent->io (
      fh   => <filehandle_or_fileno>,
      poll => <"r" or "w">,
      cb   => <callback>,
   );

手册似乎说它只能监听无论是读事件还是写事件，

我如何监听这两个事件？

Answer 1

在同一个文件句柄上安装两个不同的观察程序：r 和 w

#!/usr/bin/env perl
use strict;
use warnings;
use 5.010;

use AnyEvent;

open my $FH, '+>','test' or die $!;

my $w; $w = AnyEvent->io (
    fh   => $FH,
    poll => "w",
    cb   => sub { say "I can write!"; undef $w; },
);

my $r; $r = AnyEvent->io (
    fh   => $FH,
    poll => "r",
    cb   => sub { say "I can read!"; undef $r; },
);

AnyEvent->condvar->recv;