use CGI qw(:standard);

# Validation subroutines defined elsewhere

my %DATA = (
    field1 => [ param('field1'), \&INTEGER, 1 ], 
    field2 => [ param('field2'), \&EMAIL,   1 ], 
    field3 => [ param('field3'), \&WORD,    0 ], 
);

sub do_validation 
{
    foreach my $key (keys %DATA) {
        if($DATA{$key}[2]) {
            my @result = $DATA{$key}[1]->($DATA{$key}[0]);
            die "Didn't validate: $result[2]" unless $result[0];
        }
    }
}