Hello RCH,

As 1nickt says, when $demo has the value 'problem', each element of %distance is a Class::Measure::Length object. So the following fix should work:

    ...
    print "\nAnd here comes the result of sorting the keys of that has
+h\n";

    my $sort_function = ($demo eq 'problem')          ? 
                         sub { $distance{$b}->value <=>
                               $distance{$a}->value } :
                         sub { $distance{$b}        <=>
                               $distance{$a} };

    for my $place (sort $sort_function keys %distance)
    {
        printf "%10s is %25.15f km from here\n", $place, $distance{$pl
+ace};
    }
}
[download]

(Note that Class::Measure::Length inherits most of its methods from Class::Measure.)

Hope that helps,