php 常量const

class Sky{
    // public const name = ‘ant‘;  // 常量定义不能带修饰符
    // const name;   // 常量定义后必须赋值
    const name = ‘ant‘;
    public function __construct(){
        // echo $this->name;  // 错误
        echo self::name;
        echo Sky::name;
    }
}
//new Sky();
echo ‘<hr/>‘;

class Fly extends Sky{
    public function getSpeed(){
        echo self::name;
        echo Sky::name;
        echo parent::name;
    }
}

$fly = new Fly();
$fly->getSpeed();