carro

carro.php

<?php

class Color 
{
    private const VALID_COLORS = ["branco", "preto", "vermelho", "azul"];
    private $color;
    
    private function __construct($color) {
      $this->color = $color;
    }
    
    public static createFromString($color) 
    {
      $color = mb_strtolower($color);
      if (!in_array($color, static::VALID_COLORS)) {
        throw new OutOfBoundsException("Invalid color: $color");
      }
      
      return new static($color);
    }
}

class Car
{
    private $color;

    private function __construct(Cor $color)
    {
        $this->color = $color;             
    }
    
    public static function create($color)
    {
      // por enquanto passa, mas o ideal seria um builder =)
      return new static(Color::createFromString($color));
    }
}
 
$carro = Car::create("preto");