package Field::AltText;
use Moose;
extends 'HTML::FormHandler::Field::Text';
has 'another_attribute' => ( isa => 'Str', is => 'rw' );
sub validate
{
   my $field = shift;
   return unless $field->SUPER::validate;
   my $input = $field->input;
   my $check = $field->another_attribute;
   # do something silly
   return $field->add_error('Fails AltText validation')
       unless $input =~ m/$check/;
   return 1;
}
no Moose;
1;