public function evaluate($values)
    {
        //evaluate identifier, starts with letter, contains letters, numbers and _, ends with letter, number
        if(preg_match("/^[a-z]+[a-z_0-9]*$/", $values) === 1){
            return true;
        } else {
            if (!$this->hasOption('message')) {
                $message = empty($values)
                    ? __('The index identifier should not be empty')
                    : __('"%s" is not a valid index identifier. It must start with a letter and contain letters, numbers or underscores only', $values)
                ; 
                $this->setMessage($message);
            }
        }
        return false;
    }
public function evaluate($values)
    {
        //evaluate identifier, starts with letter, contains letters, numbers and _, ends with letter, number
        if(preg_match("/^[a-z]+[a-z_0-9]*$/", $values) === 1){
            return true;
        } else {
            if (!$this->hasOption('message')) {
                $message = empty($values)
                    ? __('The index identifier should not be empty')
                    : __('"%s" is not a valid index identifier. It must start with a letter and contain letters, numbers or underscores only', $values)
                ; 
                $this->setMessage($message);
            }
        }
        return false;
    }
public function evaluate ( $ values ) { //evaluate identifier, starts with letter, contains letters, numbers and _, ends with letter, number if ( preg_match ( "/^[a-z]+[a-z_0-9]*$/" , $ values ) === 1 ) { return true ; } else { if ( ! $ this -> hasOption ( 'message' ) ) { $ message = empty ( $ values ) ? __ ( 'The index identifier should not be empty' ) : __ ( '"%s" is not a valid index identifier. It must start with a letter and contain letters, numbers or underscores only' , $ values ) ; $ this -> setMessage ( $ message ) ; } } return false ; }
evalute the identifier

@access public
@author Joel Bout, <joel.bout@tudor.lu>
@param  values
@return boolean
evalute the identifier