drake50 has asked for the wisdom of the Perl Monks concerning the following question:

I want to be able to pass the name of a socket into a subroutine so that within that subroutine it can read from the socket. I know this is simple stuff but it's new to me.

Currently my non-working call looks something like this: 
if (&readfromsocket(*new_sock)){ do some stuff}

[download]
and within the subroutine: 
sub readfromsocket{
local $socketname = shift;
        if (defined($lineread = <$socketname>)) {do some stuff}
}

[download]

Replies are listed 'Best First'.
Re: globbing,file handles and subroutines
by webfiend (Vicar) on Mar 15, 2003 at 01:30 UTC

    Have you had a chance to look at the IO::Socket module? I believe it's part of the standard Perl distribution. Sounds like it would cover exactly what you're looking for, if you're willing to deal with object-oriented stuff :-)

    I just realized that I was using the same sig for nearly three years.

[reply]
      I'm not really sure what you're suggesting. I'm using IO::Socket to create the socket. Now I want to draw data from it by calling a function. Here is how it's created: 
      
        $sock = new IO::Socket::INET(
                   LocalHost => $myip,
                   LocalPort => $port,
                   Proto     => 'tcp',
                   Listen    => SOMAXCONN,
                   Reuse     => 1);
        $sock or die "no socket :$!";
        STDOUT->autoflush(1);
        #main loop begin
        {
        while (($new_sock, $c_addr) = $sock->accept()) {
                ($client_port, $c_ip) = sockaddr_in($c_addr);
                $client_ipnum = inet_ntoa($c_ip);
                $client_host = gethostbyaddr($c_ip, AF_INET);
                next if $kid = fork;
                die "fork: $!" unless defined $kid;
                close $sock;
                if (&readfromsocket(*new_sock)){

      [download]
      In the subroutine I could do this: 
       
      if (defined($lineread = <$new_sock>)) {whatever}

      [download]
      But I want to be able to use another var name in the subroutine.
[reply]
[d/l]
[select]
        You can simply pass the $sock to the subroutine and my it.. Its already a ref to a filehandle, hence you can work with it just like you are proposing... Here is a simple snippet to test sendmail on the local machine... 
        
use strict;
use IO::Socket;

my $sock = IO::Socket::INET->new(
   PeerAddr => '127.0.0.1',
   PeerPort => '25',
   Proto    => 'tcp',
   Type     => SOCK_STREAM
);

do_mail($sock);
print $sock "quit\n";
close($sock);

sub do_mail {
   my($handle) = shift;

   my $buf = <$handle>;

   print "Sendmail ", $buf ? "is OK\n" : "is not responding\n";

}

        [download]
        See? no alterations need to be made and the handles name is local to the sub routine.. the actual handle is still global I believe in this case, so I wouldnt suggest trying to have multiple sub routines reading the same handle at the same time..


        /* And the Creator, against his better judgement, wrote man.c */
[reply]
[d/l]
        Here is a little more info. I added the following code inside the subroutine: 
                my $socketname = shift;
        print "\$new_sock=$new_sock\n";
        print "\$socketname=$socketname\n";

        [download]
        And got this output: 
        $new_sock=IO::Socket::INET=GLOB(0x8130a94)
$socketname=*main::new_sock
        But I still don't know enough about this stuff to know what I'm doing wrong.
[reply]
[d/l]

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