use warnings;
use strict;

use DateTime;
use DateTime::Format::Strptime;

my $old_str = 'Dec 19 17:01:00 2016';
# normally, $now = DateTime->now
my $now = DateTime->new(year=>2016,month=>12,day=>19,
	hour=>17,minute=>7,second=>6,time_zone=>'America/New_York');
print "now=", $now->strftime('%Y-%m-%d-%H-%M-%S %Z'), "\n";

my $strp = DateTime::Format::Strptime->new(
	on_error=>'croak', pattern => '%b %d %T %Y',
	time_zone=>'America/New_York' );
my $old = $strp->parse_datetime($old_str);
print "old=", $old->strftime('%Y-%m-%d-%H-%M-%S %Z'), "\n";

# approach one: difference
my $diff_sec = $now->subtract_datetime_absolute($old)
	->in_units('seconds');
print "diff_sec: $diff_sec (",
	sprintf("%.1f",$diff_sec/60), " minutes)\n";

# approach two: compare to another DateTime
my $halfago = $now->clone->subtract(minutes=>30);
print "halfago=", $halfago->strftime('%Y-%m-%d-%H-%M-%S %Z'), "\n";
# note comparators are overloaded for DateTime objects
print "halfago ", ($halfago>$old?'>':'<='), " old\n";