trait

• trait 是一种特殊的类或接口

trait SayWorld
{
    public function sayWorld()
    {
        echo 'World' . PHP_EOL;
    }
}

class Base
{
    use SayWorld;

    function sayHello()
    {
        echo 'Hello' . PHP_EOL;
    }
}

$o = new Base();
$o->sayHello(); // Hello
$o->sayWorld(); // World