Type hinting for properties in PHP 7?

Question

Does php 7 support type hinting for class properties?

I mean, not just for setters/getters but for the property itself.

Something like:

Answer 1

7.4+:

Good news that it will be implemented in the new releases, as @Andrea pointed out. I will just leave this solution here in case someone wants to use it prior to 7.4

---

7.3 or less

Based on the notifications I still receive from this thread, I believe that many people out there had/is having the same issue that I had. My solution for this case was combining setters + __set magic method inside a trait in order to simulate this behaviour. Here it is:

trait SettersTrait
{
    /**
     * @param $name
     * @param $value
     */
    public function __set($name, $value)
    {
        $setter = 'set'.$name;
        if (method_exists($this, $setter)) {
            $this->$setter($value);
        } else {
            $this->$name = $value;
        }
    }
}

And here is the demonstration:

class Bar {}
class NotBar {}

class Foo
{
    use SettersTrait; //It could be implemented within this class but I used it as a trait for more flexibility

    /**
     *
     * @var Bar
     */
    private $bar;

    /**
     * @param Bar $bar
     */
    protected function setBar(Bar $bar)
    {
        //(optional) Protected so it wont be called directly by external 'entities'
        $this->bar = $bar;
    }
}

$foo = new Foo();
$foo->bar = new NotBar(); //Error
//$foo->bar = new Bar(); //Success

---

Explanation

First of all, define bar as a private property so PHP will cast __set automagically.

__set will check if there is some setter declared in the current object (method_exists($this, $setter)). Otherwise it will only set its value as it normally would.

Declare a setter method (setBar) that receives a type-hinted argument (setBar(Bar $bar)).

As long as PHP detects that something that is not Bar instance is being passed to the setter, it will automaticaly trigger a Fatal Error: Uncaught TypeError: Argument 1 passed to Foo::setBar() must be an instance of Bar, instance of NotBar given