use strict;
use CGI;

my $query=CGI->new();
my %laundry= ( 'name' => '(\w+)',
               'number' => '(\d+)',
               'choice' => ([ABC]),
             );
my %laundered_params;

foreach my $param (keys %laundry) {

  die "Parameter $param not present\n" unless my $input=$cgi->param($param);
  my $regexp=$laundry{$param};
  $input =~ /$regexp/;
  die "Invalid input for $param\n" unless $laundered_params{$param}=$1;

}