use strict;
use warnings;
use Scalar::Util qw/dualvar/;
use Hash::Util::FieldHash qw/id id_2obj register/;
use Time::Piece;

register my $t = Time::Piece::localtime; # Time::Piece object

my $x = dualvar( id( $t ), "$t" );
print "$x = ", (id_2obj($x+0))->epoch, " seconds since the epoch\n"