# val_alpha validates as [:alpha:], spaces, and hyphens.
# Usage: val_alpha \$foo [, \$bar]
sub val_alpha {
    for (@_) {
        if ($$_ =~ /^([A-Za-z -]*)$/) {
            $$_ = $1;
        }
        else {
            error_page()
        }
    }
    1;
}