PHP5, Exception in the destructor

Question

Now I am reading the book "PHP5 for Professionals", this is the 2006 edition. And in one example, they throw an exception in the destructor, for a long time I did not understand why my last exception in the destructor did not work, then I looked for it and found that in PHP => 5.3 it is not available to throw an exception in the destructor. So, how best to do this if in the destructor I update my database if the variable $needsUpdate = true; and close the database connection, so I wanted to throw an exception if the database could not be updated. For example, I throw an exception in my DB class, but I catch them in the main file, for example:

Custom Widget Class:

 class Widget { private $_id; private $_name; private $_description; private $_hDB; private $_needsUpdating = false; public function __construct($widgetID) { $this->_hDB = new mysqli('localhost', 'phpbook', 'Un+)J=<AaH', 'phpbook'); if (! $this->_hDB) { throw new Exception('     '); } $sql = "SELECT `name`, `description` FROM widgets WHERE id = '$widgetID'"; $rs = $this->_hDB->query($sql); if (! $rs) { throw new Exception("     "); } if (! $rs->num_rows) { throw new Exception("     "); } $data = $rs->fetch_assoc(); $this->_id = $widgetID; $this->_name = $data['name']; $this->_description = $data['description']; } public function getName() { return $this->_name; } public function getDescription() { return $this->_description; } public function setName($name) { $this->_name = $name; $this->_needsUpdating = true; } public function setDescription($description) { $this->_description = $description; $this->_needsUpdating = true; } public function __destruct() { if (! $this->_needsUpdating) { return; } $sql = 'UPDAT2E `widgets` SET'; $sql .= ' `name` = "' . $this->_hDB->real_escape_string($this->_name) . '",'; $sql .= ' `description` = "' . $this->_hDB->real_escape_string($this->_description) . '" '; $sql .= 'WHERE id = ' . $this->_id; $rs = $this->_hDB->query($sql); if (! $rs) { throw new Exception("     "); } $this->_hDB->close(); } } 

And this is the main file.

 try { $widget = new Widget(2); echo "Name: " . $widget->getName() . "<br />\n"; echo "Description: " . $widget->getDescription() . "<br />\n"; $widget->setName("Iphone 4 / 64GB"); $widget->setDescription("New Phone, black color, blablabla"); } catch (Exception $e) { die("An error has occurred: " . $e->getMessage()); } 

And the last exception in __destruct() does not work.

So, is there a good way to throw an exception if the update database fails? Or is there another right way, and I didn’t understand anything?

Answer 1

Exceptions in the destructor (may) lead to fatal errors. The documentation states this here: construct "> http://us.php.net/_construct

Note: Attempting to throw an exception from the destructor (called during script termination) raises a fatal error.

In most cases, you will get something like this:

 PHP Fatal error: Exception thrown without a stack frame in Unknown on line 0 

A good way to not reinvent this wheel and take, for example. Doctrine ( http://www.doctrine-project.org/ ) to help you with this task. Even if you cannot use this piece of software, you can look in the sources to find out how Benjamin does it. Take a look at EntityManager ( https://github.com/doctrine/doctrine2/blob/master/lib/Doctrine/ORM/EntityManager.php ) and UnitOfWork ( https://github.com/doctrine/doctrine2/blob/master/lib /Doctrine/ORM/UnitOfWork.php ), which are related to the processing that you mentioned in your question.