function existant_and_set($list, $keys) {

  /** For HTTP data : keys of $keys are set within $list and they are not empty

  */

  foreach($keys as $key) {

    if (!isset($list[$key]) || !$list[$key]) {

                     'lon'         => array('numeric', 'positive'),

                     'alt'  => array('numeric', 'positive'),

                     'loop'  => array('boolean'),

);

$validator = new FormValidator($fields_spec);

  $vals = $validator->sane_values();

  // There is no point setting a part of the parameters only ; check that all

  // are present.  

    try {

      $panorama = site_point::create($uploaded_filepath);

      $panorama->set_param('titre', 'Sans nom 1');//FIXME

      $panorama->set_param('longitude', $vals['lon']);

      $panorama->set_param('altitude',  $vals['alt']);

      $panorama->set_param('image_loop', $vals['loop']);

      $panorama->save_params();

      $params_success = true;

    } catch (Exception $e) {