__destruct有多可靠？

Question

Are there situations in which this method would not be called?

I'm thinking to store a important variable into a persistent cache just before the cache object gets destroyed. This variable is used many times in the page so I wouldn't like to update the cache with it every time the variable changes...

Answer 1

Let's have a class:

class A {
    public function __construct(){
        echo "Construct
";
    }

    public function __destruct(){
        echo "Destruct
";
    }
}

And test code:

$test = new A();
die( "Dead
");  // Will output Construct; dead; Destruct

$test = new A();
throw new Exception("Blah
"); // Construct, Fatal error (no destruct)

$test = new A();
require_once( 'invalid_file.php'); // Construct, Fatal error (no destruct)

So basically: there are situations (fatal errors) when destructor won't be called.

Ah and this question has the same answer as this one: When will __destruct not be called in PHP? (+/-)