$d = "Nov 25, 1971";
print "\$d contains $d\n"; # "Nov 25, 1971"
print "\$d as unixtime:", $d->to_unixtime, "\n";

##</code><code>##

Can't locate object method "to_unixtime" via package "Nov 25, 1971" (perhaps you forgot to load "Nov 25, 1971"?)

##</code><code>##

Datum->tieVar( (my $d), -type=>'date' );

$d = "Nov 25, 1971";

print STDOUT "\$d contains $d\n"; # "Nov 25, 1971"
print STDOUT "\$d as unixtime:", $d->to_unixtime, "\n";

package Datum;

use overload '""' => \&to_string;

sub tieVar {
	my $class= shift @_;
	my $toTie= \$_[0]; shift @_;
	tie $$toTie, $class, @_;
}

sub TIESCALAR {
	my $class = shift;
	my $instance = shift || undef;
	return bless \$instance => $class;
}

sub STORE {
	${$_[0]} = $_[1];
}

sub FETCH {
	# this just returns "self"
	# (won't be good in some cases)
	return $_[0];
}

sub to_string {
	# this is the "real" FETCH method 
	return ${$_[0]};
}

sub to_unixtime {
	return "foobar";
}

##</code><code>##

$d contains Nov 25, 1971
$d as unixtime:foobar