Returns TRUE if value has been changed.

Return value

Bool

Full documentation

Check if Value of 'Status' has been changed:

if ( $Order->status->isChanged() ){
    $this->get('feedback','Status has been changed!');
}

Calculate order total, if amount or price in order_rows is changed: (Returns also TRUE if deleted or added new rows.)

if ( $Order->order_rows->isChanged('amount','price') ){
    $Order->order_total = $Order->calculate('[order_rows:amount*price]');
}