Declare types explicity to variables

[jhonatanjacinto]

Hi @pronskiy , how are you doing?

I watched your presentation in Laracon EU 2024 and you mentioned this page where we could throw some ideas for discussion here. So, here it is one: is there any intention or on going work regarding defining types explicitly for variables?

The support for types in the language have been increasing along the years, so I was wondering if that would spread out to variables as well at some point like:

// this would be considered a mixed type variable
$someVar = "a string";
$someVar = 5; // no problem changing value type, as it is today

int $age = 40;
$age = "40"; // TypeError

// union types would be supported as well
string|bool $resultValue = strstr("Hello World!", "orld");

If there's no work on this kind of feature, I would like to know your thoughts (and also the community thoughts) about it. Do you think it is useful? Desirable? Problematic?

Great presentation, btw!

Thanks in advance.

[pronskiy]

@jhonatanjacinto, thanks for your kind words!

This idea has been discussed a few times in the past:
https://externals.io/message/119470

It is currently not being worked on. But it might be worth investigating for feasibility.

Meanwhile, there are some userland hacks to achieve this goal:
https://github.com/azjezz/typed/

Also, I'm wondering if you use any static analysis tools right now? How much of a benefit would it be compared to annotating the variables with PHPDoc @var?

[jhonatanjacinto]

I use PHPDoc a lot, not just to document the code base but to provide this support for the intellisense tools I use. It works well but it's a bit annoying in comparison to simply defining the type directly in the code, inline.

I strongly believe that is preferable to type...

User[] $users = UserDL::getUsers();

Then...

/** @var User[] $users*/
$users= UserDL::getUsers();

Frankly, I don't know the level of difficulty for implementing it and I understand completely if this feature would end up being too complicated to be applied to the language as it is today (or the side effects of introducing it being too bad). As an alternative, I even like an idea that is being discussed in JavaScript land which is treating types as comments, that is, the PHP interpreter would ignore these inline types but the static analysis tools would use them to provide ahead of time code checks/validation without the need of these types of comments.

All in all, I mean, everything that helps us, as developers, to catch or prevent errors/have better intellisense regarding types during the development process that is embeded already in the language, would be much appreciated. :)