Covariance in PHP

covariance.php

<?php

// Covariance - narrowing type on return. Works from PHP 7.4.0 and above
// https://www.php.net/manual/ru/language.oop5.variance.php

class Animal
{
    public function getName(): string
    {
        return 'Some animal';
    }
};

class Dog extends Animal
{
    public function getName(): string
    {
        return 'Bucky';
    }
};

class House
{
    public function getPet(): Animal
    {
        return new Animal();
    }
}


class DogHouse extends House
{
    public function getPet(): Dog
    {
        return new Dog();
    }
}


$house = new House();
echo "House pet: {$house->getPet()->getName()}\n";

$dogHouse = new DogHouse();
echo "Doghouse pet: {$dogHouse->getPet()->getName()}\n";