use Class::CGI
    handlers => {
      customer_id => 'My::Customer',
      referral_id => 'My::Customer',
      sales_date => ['My::Date::Handler', 
                      qw(sales_month sales_day sales_year)],
    };
  my $cgi  = Class::CGI->new;
  my $sales_date = $cgi->param('sales_date');
  my $customer = $cgi->param('customer_id');
  my $referrer = $cgi->param('referrar_id');