#!/usr/bin/env perl

use 5.022;
use warnings;
use feature 'refaliasing';
no warnings 'experimental::refaliasing';

@::data = (1 .. 3);

say "Data before pop_sum: @::data";
say "Sum of data: ", pop_sum(\@::data);
say "Data after pop_sum: @::data";
say '---';
say "Data before pop_sum_ref: @::data";
say "Sum of data: ", pop_sum_ref(\@::data);
say "Data after pop_sum_ref: @::data";

sub pop_sum {
    local our @data = @{+shift};

    my $total = 0;

    say "\tTotal: $total; Data: @data";

    while (1) {
        $total += pop @data;
        say "\tTotal: $total; Data: @data";
        last if $#data < 0;
    }

    return $total;
}


sub pop_sum_ref {
    \local our @data = shift;

    my $total = 0;

    say "\tTotal: $total; Data: @data";

    while (1) {
        $total += pop @data;
        say "\tTotal: $total; Data: @data";
        last if $#data < 0;
    }

    return $total;
}