/**
 * form 
 */
function myzend_form($form_state){
 
  $form['mail'] = array(
    '#type' => 'textfield', 
    '#title' => t('mail'), 
    '#default_value' => variable_get('mail', null),
    '#description' => t('Entrer votre adresse mail'),
    '#zend' => 'Zend_Validate_EmailAddress',
  );
 
 
  $form['submit'] = array(
    '#type' => 'submit', 
    '#value' => t('Save'), 
  );
 
 
  return $form;
}
 
/**
 * Validate
 */
function myzend_form_validate($form,&$form_state){  
 
  //automated validation zend
  foreach($form as $key => $value){
    //check if have a zend validation    
    if(!is_array($value) || !isset($value['#zend'])){
      continue;
    }
    //get the value
    $val = $form_state['values'][$key];
 
    //load the class zend
    if(zend_initialize($value['#zend']) && zend_initialize('Zend_Validate_Abstract')){
 
      //initialize the validator
      $validator = new $value['#zend'](); 
 
      //check if is the good instance
      if(!$validator instanceof Zend_Validate_Abstract){
        form_set_error($key,t('Erreur'));
      }
 
      //validate
      if (!$validator->isValid($val)) {
        foreach ($validator->getMessages() as $messageId => $message) {
          form_set_error($key, t("Validation failure '$messageId': $message"));
        }
      }
    } 
  }
}