外部メソッドを PHP クラスに含めることはできますか? 最良の代替方法は何ですか?

// MeowingInterface.php
interface MeowingInterface
{
    public function meow(): string;
}

// RegularMeow.php
class RegularMeow implements MeowingInterface
{
    public function meow(): string
    {
        return 'meow';
    }
}

// LolcatMeow.php
class LolcatMeow implements MeowingInterface
{
    public function meow(): string
    {
        return 'lolz xD';
    }
}

// Cat.php
class Cat
{
    private MeowingInterface $meowingBehaviour;

    public function setMeowingBehaviour(MeowingInterface $meowingBehaviour): void
    {
        $this->meowingBehaviour = $meowingBehaviour;
    }

    public function meow(): string
    {
        return $this->meowingBehaviour->meow();
    }
}

// index.php
require_once 'MeowingInterface.php';
require_once 'RegularMeow.php';
require_once 'LolcatMeow.php';
require_once 'Cat.php';

$cat = new Cat();
$cat->setMeowingBehaviour(new RegularMeow());
echo $cat->meow(); // Outputs "meow"

// Change behaviour
$cat->setMeowingBehaviour(new LolcatMeow());
echo $cat->meow(); // Outputs "lolz xD"