$blocking = $sock->blocking(0) if $timeout;

##</code><code>##


use strict;
use warnings;

use IO::Socket;


sub show_blocking_result {
   my ($blocking) = @_;

   die("Error switching to non-blocking: $!\n")
      if not defined $blocking;

   printf("Was previously: %s\n",
      ($blocking ? "blocking" : "non-blocking"),
   );
}


my $sock = new IO::Socket::INET(
   PeerAddr => "www.perlmonks.org",
   PeerPort => 80,
   Proto => 'tcp',
);

die("Error connecting: $!\n")
  if not defined $sock;

# We didn't turn off blocking mode,
# so the following should return true.
show_blocking_result($sock->blocking(0));

# Should return false, but presumably defined.
show_blocking_result($sock->blocking(1));


__END__

Windows
-------
Error switching to non-blocking:

FreeBSD
-------
Was previously: blocking
Was previously: non-blocking