ちなみに、Parser.pmはこんな感じです↓

package Common::Parser;

sub new {
my $class = shift;

my $self = {
query => undef
};

bless $self, $class;

if ($ENV{'CONTENT_LENGTH'} or $ENV{'QUERY_STRING'}) {
$self->{query} = $self->_parse_query;
}
}