How do tell Perl to break only on undef?

[myuserid7]

Hello, while working on a package I ran into a problem for which I could not find a pretty solution. I broke things down to come up with the example code below to demonstrate my issue. When this script is executed, it will print only "12568", because 0 is considered as false and this breaks the while loop. Now I could use while(1) and add some more lines to check $i for undef and then do a "last", but the package is supposed to be used by others so I want to keep it as simple as possible. What would be a pretty/easy way to make while only treat undef as a breaking argument?

#!/usr/bin/perl -w
use strict;
use warnings;

my $t = test->new();
while (my $i = $t->get) { print $i; };

package test;
use strict;
use warnings;

my @list;

sub new {
    my $self = shift;
    my $this = {};
    @list = ( 1, 2, 5, 6, 8, 0, 9 );
    bless($this, $self);
    return($this);
    };

sub get {
    return(shift(@list)); 
    };
1;

[choroba]

That's why Perl has defined:

while (defined( my $i = $t->get )) { print $i; };

[myuserid7]

I cannot believe I forgot defined
Thanks!