通过Net::Ping 理解Perl的面向对象

<pre name="code" class="sql">v-dev-redis01:/root# cat a1.pl sub check_dns{ use  LWP::UserAgent;  use Net::Ping;$web = shift; $p = Net::Ping->new("icmp");  if ($p->ping($web,2)){   return 1;}  else {  return 0;}} ;$var=&check_dns("$ARGV[0]"); print "$var\n";v-dev-redis01:/root# perl a1.pl  www.zjtest.com1       If a default timeout ($def_timeout) in seconds is provided, it is used when a timeout is not given to the ping() method (below).  The timeout must be greater than 0 and the default, if           not specified, is 5 seconds.jrhmpt01:/root# cat a3.pl use Net::Ping;$p = Net::Ping->new("icmp");use Data::Dumper;   my $xx= Dumper($p);      print "111111111\n";  print $xx;      print "\n"; jrhmpt01:/root# perl a3.pl 111111111$VAR1 = bless( {                 'proto_num' => 1,                 'proto' => 'icmp',                 'data' => '',                 'device' => undef,                 'tos' => undef,                 'data_size' => 0,                 'pid' => 30484,                 'econnrefused' => undef,                 'fh' => bless( \*Symbol::GEN0, 'FileHandle' ),                 'timeout' => 5,                 'local_addr' => undef,                 'seq' => 0,                 'retrans' => '1.2'               }, 'Net::Ping' );生产$p 这个对象,sub new{  my ($this,      $proto,             # Optional protocol to use for pinging      $timeout,           # Optional timeout in seconds      $data_size,         # Optional additional bytes of data      $device,            # Optional device to use      $tos,               # Optional ToS to set      ) = @_;  my  $class = ref($this) || $this;  my  $self = {};  my ($cnt,               # Count through data bytes      $min_datasize       # Minimum data bytes required      );  bless($self, $class);其中$class is Net::Ping$self 是$VAR1 = bless( {}, 'Net::Ping' );sub ping{  my ($self,      $host,              # Name or IP number of host to ping      $timeout,           # Seconds after which ping times out      ) = @_;  my ($ip,                # Packed IP number of $host      $ret,               # The return value      $ping_time,         # When ping began      );ping 方法的第一个参数是$self 对象第2个参数是  域名或者IP地址第三个参数是  超时秒数生产$p 这个对象,  Functions       Net::Ping->new([$proto [, $def_timeout [, $bytes [, $device [, $tos ]]]]]);           Create a new ping object.  All of the parameters are optional.  $proto specifies the protocol to use when doing a ping.  The current choices are "tcp", "udp", "icmp", "stream", "syn",           or "external".  The default is "tcp".创建一个new 的ping 对象