Question

the php manual states:

It can clean up the object and is
supposed to return an array with the
names of all variables of that object
that should be serialized.

i understand this as, if a had a class. Like this:

<?php

class Foo {

    public $bar = 'bar';

    public $baz = 'baz';

    public function __sleep() {
        return array('bar');
    }

}

$obj = new Foo();
$serialized = serialize($obj);
$unserialized = unserialize($serialized);

var_dump($unserialized);

?>

it would only serialize the object and the property $bar? Like this:

object(Foo)[2]
  public 'bar' => string 'bar' (length=3)

but it returns:

object(Foo)[2]
  public 'bar' => string 'bar' (length=3)
  public 'baz' => string 'baz' (length=3)

Have i interpreted it wrong? Or am i doing it wrong or what?

Answer 1

Unserializing creates a new instance of the object, and since your definition of the class initializes the attribute, you’re getting a default value for it. Try this:

class Foo {
    public $bar;
    public $baz;
    public function __sleep()
    {
        return array('bar');
    }
}

$obj = new Foo();
$obj->bar = 'bar';
$obj->baz = 'baz';
$serialized = serialize($obj);
$unserialized = unserialize($serialized);
var_dump($unserialized);

Edit: Alternatively, you can vardump($serialized) and see that there is no baz in it.