Programming PHP

Here are some sample classes and objects that exercise the introspection functions
from Example 6-2:
class A {
var $foo = 'foo';
var $bar = 'bar';
var $baz = 17.0;
function first_function( ) { }
function second_function( ) { }
};
class B extends A {
var $quux = false;
function third_function( ) { }
};
class C extends B {
};
$a = new A;
$a->foo = 'sylvie';
$a->bar = 23;
$b = new B;
$b->foo = 'bruno';
$b->quux = true;
$c = new C;
print_object_info($a);
print_object_info($b);
print_object_info($c);
Figure 6-2 shows the output of this code.
Serialization
Serializing an object means converting it to a bytestream representation that can be
stored in a file. This is useful for persistent data; for example, PHP sessions automaticallysave
and restore objects. Serialization in PHP is mostlyautomatic—it requires little
extra work from you, beyond calling the serialize( ) and unserialize( ) functions:
$encoded = serialize(something);
$something = unserialize(encoded);
Serialization is most commonlyused with PHP’s sessions, which handle the serialization
for you. All you need to do is tell PHP which variables to keep track of, and
they’re automatically preserved between visits to pages on your site. However, sessions
are not the only use of serialization—if you want to implement your own form of
persistent objects, the serialize( ) and unserialize( ) functions are a natural choice.
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Serialization | 153