<?php declare(strict_types=1);

// /app/family/Father.php
namespace app\family;

class Father
{
    protected $name;
    protected function with(string $name, $value): Father
    {
        $new = clone $this;
        $new->{$name} = $value;
        return $new;
    }
    public function withName(string $name): Father { return $this->with('name', $name); }
    public function __toString(): string { return "{$this->name}\n"; }
}

// /app/family/Daughter.php
namespace app\family;

class Daughter extends Father
{
    protected $hair;
    protected $name;
    public function __toString(): string { return "{$this->name} has {$this->hair} hair.\n"; }
    public function withHair(string $hair): Daughter { return $this->with('hair', $hair); }
}

// Some usage=
use app\family\Daughter;
$d = new Daughter;
$d1 = $d->withHair('golden')->withName('Sofia');
$d2 = $d->withName('Mari')->withHair('dark');
echo $d1 . $d2 ;