# [RFC] Nullsafe calls

- Thread: https://externals.io/message/79600
- Original archive: https://news-web.php.net/php.internals/79600
- Started by Thomas Bley on 2014-12-12T15:42:33+00:00
- Messages: 2
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## #79600 — Thomas Bley — 2014-12-12T15:42:33+00:00

URL: https://externals.io/message/79600#79600

Hello Josh,

1) I think it would be better to have ObjectSafe Calls, e.g.

class User {
  ...
  public function delete() {
    // delete ...
  }
}
class Users {
  public function find($id) {
    if ($this->db->query(...)) return new User($id);
    return 'not found';
  }
}

$users = new Users();
$result = $users->find(42)?->delete(); // $result = 'not found';

That way we can use scalars as return for further processing.

Definition:
Calling $obj?->foo(..) behaves identically to $obj->foo(..) if $obj is an object. If $obj is not an $object, then it returns $obj.


2) Another approach would to implement this in user land:

class Failure {
  public function __construct($msg) {
    $this->msg = $msg;
  }
  public function __call($name, $args) {
    return $this;
  }
}
class User {
  ...
  public function delete() {
    // delete ...
  }
}
class Users {
  public function find($id) {
    if ($this->db->query(...)) return new User($id);
    return new Failure('not found');
  }
}

$users = new Users();
$result = $users->find(42)->delete();
// do sth...
if ($result instanceof Failure) {
  echo $result->msg; // not found
}

Regards
Thomas


Josh Watzman wrote on 10.12.2014 00:07:

> Hey internals! A useful feature that Hack picked up in the last few months are
> "nullsafe calls", a way of propagating failure forward in a series of chained
> method calls to the end of the whole computation, getting rid of a lot of the
> boilerplate in the middle. I think the feature would be a good one for PHP as
> well, so I'm submitting this RFC to add it -- you can see the RFC itself for a
> full discussion of the motivation for the feature, as well as the feature
> itself:
> 
> https://wiki.php.net/rfc/nullsafe_calls
> 
> Josh Watzman

---

## #79602 — Andrea Faulds — 2014-12-12T16:13:27+00:00

URL: https://externals.io/message/79600#79602 · In reply to: #79600

Hi Thomas,

> 
> 
> 1) I think it would be better to have ObjectSafe Calls, e.g.
> 
> class User {
>  ...
>  public function delete() {
>    // delete ...
>  }
> }
> class Users {
>  public function find($id) {
>    if ($this->db->query(...)) return new User($id);
>    return 'not found';
>  }
> }
> 
> $users = new Users();
> $result = $users->find(42)?->delete(); // $result = 'not found';
> 
> That way we can use scalars as return for further processing.
> 
> Definition:
> Calling $obj?->foo(..) behaves identically to $obj->foo(..) if $obj is an object. If $obj is not an $object, then it returns $obj.

This would prevent adding methods for scalars or arrays in future, so I don’t like it.

Thanks.
--
Andrea Faulds
http://ajf.me/