Thanks a lot for your feedback. I like the clone idea too and I also see no harm in allowing them in any context rather than only in immutable classes. I am really against the transformer keyword, don't ask me why, I just don't like it at all. :P
I mentioned before that PHP should allow for operator overloading since there are other value object use cases that are even simpler than your HTTP header result: any value object that is case insensitive. Doh! I do like the https://wiki.php.net/rfc/comparable RFC but we would need more for value objects to be truly useful. class A { // $this == $other function __isEqual($other); // $this === $other function __isIdentical($other); } This will be very hard to get through though because it's operator overloading. I am currently already doing this in many of my value objects, although I usually implement an equals method only and let it take care of equals and identity checks at the same time. final class HexNumber { private $val; public function __construct(string $hex) { $this->val = strtolower($hex); } public function equals($other) { if ($other instanceof self) { return $other->val === $this->val; } if (is_string($other)) { return strtolower($other) === $this->val; } return false; } } $hn = new HexNumber('ff00'); var_dump($hn->equals('FF00')); // bool(true) However, this is not necessarily exactly what you want in every context, hence, the proposal for operator overloading. That being said, I agree that this could (and probably should) be tackled in another RFC. Immutable classes do not have to solve every problem. -- Richard "Fleshgrinder" Fussenegger
signature.asc
Description: OpenPGP digital signature
