__clone

Like the constructor, __clone is invoked by a PHP operator, in this case clone. This is a new operator introduced with PHP 5. To see why it is necessary, we need to take a look at how objects are copied in PHP 4.

In PHP 4 objects are copied in exactly the same way that regular variables are copied. To illustrate, let's reuse the Person class shown in Listing 13-1 (see Listing 13-3).

Listing 13-3. Using the assignment operator under PHP 4
$x = 3;
$y = $x;
$y = 4;
echo $x. '<br />';
echo $y. '<br />';
$obj1 = new Person();
$obj1->name = 'Waldo';
$obj2 ❶= $obj1;
$obj2->name = 'Tom';
echo $obj1->name. '<br />';
echo $obj2->name;

If the code in Listing 13-3 is run under PHP 4, the output will be as follows:

				3
				4
				Waldo
				Tom

The assignment ...

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