<?php

class Car {

    public $speed = 10;

    //在这里使用重载实现speedDown方法

    public function __call($name, $args) {

        if ($name == 'speedDown') {

            $this->speed -=10;

        }

}

$car = new Car();

$car->speedDown(); //调用不存在的speedDown方法

echo $car->speed;