Question

Should I use E_NOTICE enabled on live server?

As I can see in Why should I fix E_NOTICE errors?
everybody is again with using isset() to omit notices. I have read pros, but how about code readability?

Let’s examine some code:

if ($this->_oldattributes['category_id'] != $tattr['category_id']
    || $this->_oldattributes['deal_id'] != $tattr['deal_id']
) {

Clear to understand what I want here, right?

Lets add isset() to omit notices:

$old_cat_id = isset($this->_oldattributes['category_id']) ? $this->_oldattributes['category_id'] : null;
$new_cat_id = isset($tattr['category_id']) ? $tattr['category_id'] : null;
$old_deal_id = isset($this->_oldattributes['deal_id']) ? $this->_oldattributes['deal_id'] : null;
$new_deal_id = isset($tattr['deal_id']) ? $tattr['deal_id'] : null;
if ($old_cat_id != $new_cat_id || $old_deal_id != $new_deal_id) {

Not bad, but now I need more time to understand what is happening here.

A few bits about debugging – I never wasted a day to debug errors caused by not initialized variable. Yes, maybe half of a hour was wasted to slide down into the classes/functions but this not a big waste when comparing to losing code readability IMHO?

A few bits about performance – http://seanmonstar.com/post/909029460/php-error-suppression-performance

The difference was that suppressing the notice took 100% as long as just checking if it existed first”
Test was performed on 1000000 supressions. How many of them appears in your code, even if you use Zend+Doctrine+something else? And how many time does it takes in comparison to DB connections, etc.?

Maybe I just not used to write correct code(used only PHP for long time now).

For context we have moved our project to server which displaying E_NOTICEs, that’s why I’m asking this. I don’t know why this is a big problem to switch them off?

Another example:

class Item extends CActiveRecord {
    private $_oldattributes = array();

public function afterFind()
{
    // Save old values
    $this->_oldattributes = $this->getAttributes();
    $this->_oldcategory = $this->category;
    $this->_olddeal = $this->deal;
}

so I will have null if old attributes not exists
and:

$tattr = $this->getAttributes();
$this->_oldattributes['category_id'] != $tattr['category_id']

which will give me what I need, and there are no errors, right?

Same with not an object error, in Yii when I have set up relations some objects may not be initialized, yes there is a kind of error, because have null value and not initialized in this case is real error sometimes:

$this->deal->item->id != $this->_olddeal->item->id

This may trigger a notice but will work as intended, so you ignore the notice:

if ($_GET['foo']) ...

The problem is that I can’t ignore this, because it still throws notice
and every time when i use this I must write:

if (isset($_GET['foo']) && $_GET['foo']) ...

or:

if (@$_GET['foo']) ...

Answer 1

When I look at your code, for example

$this->_oldattributes['category_id']

my first thought was, that this should probably be a class instead.

class Attributes {
  public $categoryId;
  // and so on
}

The difference now is, that don’t need to use isset() anymore, because now the property exists (maybe it’s null) or it is definetely a bug (“Undefined property”) and should be fixed. I think most of your cases, that you “fixed” with isset(), are of this kind.