php __clone实现

<?php

class Account {

    public $balance;

    public function __construct($balance) {
        $this->balance = $balance;
    }

}

class Person {

    private $id;
    private $name;
    private $age;
    public $account;

    public function __construct($name, $age, Account $account) {
        $this->name = $name;
        $this->age = $age;
        $this->account = $account;
    }

    public function setId($id) {
        $this->id = $id;
    }

    public function __clone() {    //复制方法,可在里面定义再clone是进行的操作
        $this->id = 0;
        $this->account = clone $this->account;    //不加这一句,account在clone是会只被复制引用,其中一个account的balance被修改另一个也同样会被修改
    }

}

$person = new Person("peter", 15, new Account(1000));

$person->setId(1);
$person2 = clone $person;

$person2->account->balance = 250;

echo '<pre>';
var_dump($person, $person2);
?>

结果
object(Person)#1 (4) {
  ["id":"Person":private]=>
  int(1)
  ["name":"Person":private]=>
  string(5) "peter"
  ["age":"Person":private]=>
  int(15)
  ["account"]=>
  object(Account)#2 (1) {
    ["balance"]=>
    int(1000)
  }
}
object(Person)#3 (4) {
  ["id":"Person":private]=>
  int(0)
  ["name":"Person":private]=>
  string(5) "peter"
  ["age":"Person":private]=>
  int(15)
  ["account"]=>
  object(Account)#4 (1) {
    ["balance"]=>
    int(250)
  }
}