[RFC] Nullsafe operator

On 02/06/2020 22:52, Ilija Tovilo wrote:

I like it a lot! Concise and clear RFC. From having used a similar feature in TypeScript I can say it is quite convenient, easy to get used to and makes for much leaner code. IMO not having it on array accesses isn't so bad as with arrays you can easily isset($deep['into']['the']['array']) in one go, while with objects and getters etc it tends to lead to much uglier and repetitive code like:     if ($foo && $foo->getBar() && $foo->getBar()->getBaz()) { ... } So yeah, +1 Best, Jordi

On Tue, Jun 2, 2020 at 10:53 PM Ilija Tovilo <tovilo.ilija@gmail.com> wrote:

The semantics look reasonable to me, but I'd recommend including some discussion on the rationale behind the short-circuiting behavior in the RFC. That is, what the options are, and why this is the best option (which is not the option that the previous RFC on this topic picked). It would also be nice to cross-reference semantics of ?-> in other languages that have it, to make sure we don't introduce any unexpected WTFs for people switching between languages. I *think* the specified behavior is consistent with what everyone else does, but I haven't checked to be sure. Regards, Nikita

Hi Internals, Wouldn't it make more sense to make `isset` smarter? So that it can handle these situations just like it would with array access. That way you could use the null coalescing operator as well. I don't see many situations where you would be selective in which method in the chain you would want to make nullsafe and which ones you wouldn't. I think it would mostly be the entire chain, in which case using `??` would be much less verbose. In the few cases where you want to be specific in which are nullsafe and which ones aren't you can introduce one more variable. Using the first example in the RFC this would visully be far nicer and more readable about the intent: $country = $session->user->getAddress()->country ?? null; Besides, shouldn't the example really be: $user->getAddressCountry(); I don't recall ever having to nest three levels like that example. I know the example is contrived, but wouldn't you know if you have a logged in user or not? Then just have a simple getter on the user for what you need to check. Chances are those variables you're trying to save will be used elsewhere, or if not, refactor. Also, assuming we have control over the User class, you can either make address a property or use the magic getters (that many frameworks have, love or hate them). Even the new new accepted Constructor Property Promotion would be helpful in facilitating that. Basically we can easily get around this problem already, and some frameworks do it by default. If not, writing one getter where you have to check a few things is IMO far nicer than a long chain of possibly null objects. This is how I would solve the issue, assuming we're just in the controller we don't make anything specifically for the User or Address classes and no other uses for those specifically are needed. protected function getCountry() { $user = $this->session->user ?? null; if ($user === null) $this->redirectToLogin(); if ($user->getAddress() === null) return null; return $user->getAddress()->country ?? null; } Chaining that many objects together that may or may not be null just seems so wrong to me. My concern is that we would start seeing `?->` far too often and it would promote some lazy habits, because people would add it "just in case". Personally I think it should be more explicit when we are null-checking, and since the `->` object access usually doesn't have spaces around it, it could "muddy the water". It reminds me too much of the proposed "unary null coalescing operator", which also reminds me of the error control operator. Maybe make the syntax `->@` to be more clear? Sorry if I come off a bit harsh, but I don't see the need for this as other solutions to this problem are more favourable IMHO. As much as it can be annoying sometimes, the `Call to a member function foo() on null` is a very useful error. Thanks, Peter

BIG THUMBS UP for this feature. As was mentioned that TypeScript uses this and saves developers lots of time by avoiding nested null checking. I suggest in the RFC including a list of other languages that have this feature. On Tue, Jun 2, 2020, 2:53 PM Ilija Tovilo <tovilo.ilija@gmail.com> wrote:

Hi internals

I've reworded some things and added more information on short circuiting. Functionality wise the RFC has remained the same. Since there was little negative feedback I'd like to put this feature to a vote in ~1 week. If you have any concerns or criticism please let me know in time. Ilija

Hi Ilija,

Would this still work together with short-circuiting and the null coalesce operator? I just didn't see a clear example about this but also figured that could be a practical way to use this: ```php $country = $session?->user?->getAddress()?->country ?? 'defaultCountry'; ``` (hope the example is readable, my MUA insists on wrapping the lines) thanks, - Markus