[RFC] Nullsafe calls

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