输出：
User Object ( [group:DomainObject:private] => default ) SpreadSheet Object ( [group:DomainObject:private] => document )
final字段
使类无法被继承，用的不多
<?php
final class Checkout { // 终止类的继承
// ...
}
class IllegalCheckout extends Checkout {
// ...
}
$checkout = new Checkout();
?>
输出：
Fatal error: Class IllegalCheckout may not inherit from final class (Checkout)
final方法不能够被重写
<?php
class Checkout {
final function totalize() {
// calculate bill
}
}
class IllegalCheckout extends Checkout {
function totalize() { // 不能重写final方法
// change bill calculation
}
}
$checkout = new Checkout();
?>
输出：
Fatal error: Cannot override final method Checkout::totalize()
析构函数
<?php
class Person {
protected $name;
private $age;
private $id;
function __construct( $name, $age ) {
$this->name = $name;
$this->age = $age;
}
function setId( $id ) {
$this->id = $id;
}
function __destruct() { // 析构函数
if ( ! empty( $this->id ) ) {
// save Person data
print "saving personn";
}
if ( empty( $this->id ) ) {
// save Person data
print "do nothingn";
}
}
}
$person = new Person( "bob", 44 );
$person->setId( 343 );
$person->setId( '' ); // 最后执行析构函数，使用完之后执行
?>
输出：
do nothing
__clone方法
克隆的时候执行
<?php
class Person {
private $name;
private $age;
private $id;
function __construct( $name, $age ) {
$this->name = $name;
$this->age = $age;
}
function setId( $id ) {
$this->id = $id;
}
function __clone() { // 克隆时候执行
$this->id = 0;
}
}
$person = new Person( "bob", 44 );
$person->setId( 343 );
$person2 = clone $person;
print_r( $person );
print_r( $person2 );
?>
输出：
Person Object ( [name:Person:private] => bob [age:Person:private] => 44 [id:Person:private] => 343 ) Person Object ( [name:Person:private] => bob [age:Person:private] => 44 [id:Person:private] => 0 )
再看一个例子
<?php
class Account { // 账户类
public $balance; // 余额
function __construct( $balance ) {
$this->balance = $balance;
}
}
class Person {
private $name;
private $age;
private $id;
public $account;
function __construct( $name, $age, Account $account ) {
$this->name = $name;
$this->age = $age;
$this->account = $account;
}
function setId( $id ) {
$this->id = $id;
}
function __clone() {
$this->id = 0;
}
}
$person = new Person( "bob", 44, new Account( 200 ) ); // 以类对象作为参数
$person->setId( 343 );
$person2 = clone $person;
// give $person some money
$person->account->balance += 10;
// $person2 sees the credit too
print $person2->account->balance; // person的属性account也是一个类，他的属性balance的值是210
// output:
// 210
?>
