Zend_Validate_StringLength::setMin PHP Méthode

    public function setMin($min)
    {
        if (null !== $this->_max && $min > $this->_max) {
            /**
             * @see Zend_Validate_Exception
             */
            require_once 'Zend/Validate/Exception.php';
            throw new Zend_Validate_Exception("The minimum must be less than or equal to the maximum length, but {$min} >" . " {$this->_max}");
        }
        $this->_min = max(0, (int) $min);
        return $this;
    }

 /**
  * Overrides init() in Zend_Form
  * 
  * @access public
  * @return void
  */
 public function init()
 {
     // init the parent
     parent::init();
     // set the form's method
     $this->setMethod('post');
     $user = Zend_Auth::getInstance()->getIdentity();
     $oldPasswordValidator = new App_Validate_PasswordExists(array('table' => 'backoffice_users', 'field' => 'password', 'treatment' => 'BackofficeUser::hashPassword', 'userPkValue' => $user->id));
     $complexityValidator = new Zend_Validate_Regex('/^(?=.*\\d)(?=.*[a-z|A-Z]).{7,}$/');
     $complexityValidator->setMessage('The selected password does not meet the required complexity requirements');
     $stringLengthValidator = new Zend_Validate_StringLength();
     $stringLengthValidator->setMin(7);
     $stringLengthValidator->setMessage('Your password must be at least 7 characters long');
     $passwordHistoryValidator = new App_Validate_NoPasswordExists(array('table' => 'password_log', 'field' => 'password', 'treatment' => 'BackofficeUser::hashPassword', 'userPkField' => 'user_id', 'userPkValue' => $user->id));
     $oldPassword = new Zend_Form_Element_Password('old_password');
     $oldPassword->setOptions(array('label' => $this->t('Old password'), 'required' => TRUE, 'filters' => array('StringTrim', 'StripTags'), 'validators' => array('NotEmpty', $oldPasswordValidator)));
     $this->addElement($oldPassword);
     $password = new Zend_Form_Element_Password('password');
     $password->setOptions(array('label' => $this->t('New password'), 'required' => TRUE, 'filters' => array('StringTrim', 'StripTags'), 'validators' => array('NotEmpty', $stringLengthValidator, $complexityValidator, $passwordHistoryValidator)));
     $this->addElement($password);
     $sameAsValidator = new App_Validate_SameAs($password);
     $sameAsValidator->setMessage('The two passwords do not coincide.', App_Validate_SameAs::NOT_THE_SAME);
     $retypeNewPassword = new Zend_Form_Element_Password('retype_new_password');
     $retypeNewPassword->setOptions(array('label' => $this->t('Retype new password'), 'required' => TRUE, 'filters' => array('StringTrim', 'StripTags'), 'validators' => array('NotEmpty', $sameAsValidator)));
     $this->addElement($retypeNewPassword);
     $submit = new Zend_Form_Element_Submit('submit');
     $submit->setOptions(array('label' => $this->t('Save password'), 'required' => TRUE));
     $this->addElement($submit);
 }