PHP重载

class Car {
private $ary = array();

public function __set($key, $val) {
$this->ary[$key] = $val;
}

public function __get($key) {
if (isset($this->ary[$key])) {
return $this->ary[$key];
}
return null;
}

public function __isset($key) {
if (isset($this->ary[$key])) {
return true;
}
return false;
}

public function __unset($key) {
unset($this->ary[$key]);
}
}
$car = new Car();
$car->name = '汽车';  //name属性动态创建并赋值
echo $car->name;

class Car {
public $speed = 0;

public function __call($name, $args) {
if ($name == 'speedUp') {
$this->speed += 10;
}
}
}
$car = new Car();
$car->speedUp(); //调用不存在的方法会使用重载
echo $car->speed;