You can quickly get %param using a single line:

my %param = $q->Vars();

These params can be sorted based on a pre-defined order, something not unlike:

my @order = qw[ firstname lastname age shoesize ];
my %ordered_param = map { $_ => 1 } @order;

foreach (@order, sort grep { !$ordered_param{$_} } keys %param)
{
     print "$_ $param{$_}\n";
}
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This will show your ordered parameters, followed by any unordered parameters in alphabetical order.