Re: Help understand documentation

On Jun 11, 2006, at 14:20, Vijay Kumar Adhikari wrote:

This is from http://perldoc.perl.org/Net/Ping.html

# Like tcp protocol, but with many hosts
$p = Net::Ping->new("syn");
$p->{port_num} = getservbyname("http", "tcp");
foreach $host (@host_array) {
$p->ping($host);
}
while (($host,$rtt,$ip) = $p->ack) {
print "HOST: $host [$ip] ACKed in $rtt seconds.\n";
}

Can some body tell me what the following line does?
$p->{port_num} = getservbyname("http", "tcp");

The object in $p is a blessed hashref. That's Perl object-oriented jargon, if you are not familiar with it think $p is a regular hashref. In any case,

$p->{port_num} = $value;

assigns $value to the key "port_num" of the hash %$p.

That usage is a bit unusual, normally the underlying implementation of an object is not public for clients, and access to its "attributes" in the case of hashrefs is normally encapsulated in method calls.

Anyway, that's what that code means.

-- fxn


.

Relevant Pages