A short example from the recent Perl6 calendar[1]:

Perl5:

    package Timer;
    
    use Time::HiRes qw(gettimeofday tv_interval);
    use Mojo::Base -base;
    use experimental 'signatures', 'postderef';
    
    has _event_log  => sub { [] };
    has _start_time => sub { [ gettimeofday ] };
    
    sub record ($self, $event_description) {
        # record the event and timestamp
        my $event = {
            timestamp   => sprintf('%.3f', tv_interval($self->_start_time)),
            description => $event_description,
        };
        push($self->_event_log->@*, $event);
    }
    
    sub report ($self) {
        # render a full report
        my $report = '';
        foreach my $event ($self->_event_log->@*) {
            $report .= sprintf "[%s] %s\n", $event->{timestamp}, $event->{description};
        }
        return $report;
    }
    1;

    class Timer {
        has $!start-time;
        has @!event-log;
    
        method record ($event_description) {
            # initialise the start-time if this is the first time through
            $!start-time //= now;
            @!event-log.push({
                timestamp   => now - $!start-time,
                description => $event_description
            });
        }
        method report {
            my @report_lines;
            for @!event-log -> %event {
                 @report_lines.push("[%event<timestamp>.fmt("%.3f")] %event<description>");
            }
            return @report_lines.join("\n");
        }
    }