Perl Net::FTP object expected re-use behavior? - perl

Question

I can't seem to re-use a Net::FTP object after using quit.
Is this expected? I was unable to tell from the documentation (cpan).
As a workaround, I'm creating a new Net::FTP object each time I need to perform a batch of ftp operations. This seems wasteful.
The following example shows: successful initial login, printing of root directory ls, quit (socket close), login failing with ftp message "Connection closed".
#!/usr/bin/env perl
use strict;
use warnings;
use Net::FTP;
my $hostname = 'foo';
my $username = 'bar';
my $password = 'baz';
# successful first pass
my $ftp = Net::FTP->new( $hostname ) or die "cannot connect to $hostname: $#";
$ftp->login( $username, $password ) or die "cannot login: ", $ftp->message;
map { print "ls_output: $_\n" } $ftp->ls; # success
$ftp->quit or die "cannot close connection: ", $ftp->message;
# re-use attempt
$ftp->login( $username, $password ) or die "cannot login: ", $ftp->message;
# never gets here since re-use attempt fails
print "done!\n";

Answer 1

quit causes the remote end to close the connection and there's no way to logout without closing the connection. If you're trying to avoid reconnecting, you can't.
On the other hand, maybe you're expecting login to connect you to the server. The connection is created in new, not in login, and Net::FTP does not provide a means of reconnecting.
Net::FTP subclasses IO::Socket::INET, so you could reconnect by using IO::Socket::INET's connect, but you'd also have to reinitialise a field or two the constructor normally initialises. Nothing complicated though.
But is there even a problem that needs fixing? You talk of inefficiencies, but the time it takes to create and initialise an object pales in comparison it takes to make an FTP connection.

Answer 2

It's not a Perl issue. It's the FTP protocol. After the quit is issued... that's it, the FTP session is over. There's nothing to issue the login command to -- no-one's listening anymore.
Try it yourself on the command line with the FTP client.

Answer 3

From this very documentation you linked:
quit ()
Send the QUIT command to the remote FTP server and close the socket connection.
Closing the socket connection terminates the connection to the server, not just the session on this server.
Creating a new object for each connection has two drawbacks:
Perl may or may not keep the data from the old object around in memory—but garbage collection should not bother you.
Creating a new connection involves some overhead. But unless you are creating dozens of new connections per second, this should not bother you.
So just create new objects every time; you can reuse the same variable if you like. Thinking too low level in Perl, and optimizing too early is only going to hurt.