_proc => $action1,

##</code><code>##

_proc => \$action1,

##</code><code>##

package Engine;
use strict;
use My::Module;

my $action1 = sub
{
    $pkt = shift; #where $pkt is an object of type My:Module:Object
    my $id = $pkt->get('ID');
    #........
    #do this 
    #do that...
    print $id;
}

sub new
{
    my $class = @_;
    return bless {
        _xp => My::Module->new(),
        _proc => $action1,
    }
};

sub routine
{
    my $s = shift;
    $s->{_xp}->process();
    my @arr = $s->{_xp}->getvalues("packet");
    
    map($action1->($_), @arr);
}