How does property chaining in between methods work in php

I understand how chaining methods works, I also understand how chaining a property as the last item in the chain works, like this example

$tank = $bmw -> fill(10) -> ride(40) -> tank;

but what about chaining a property in between two methods, how does that work? is the property secretly a method? here is an example

expect(2,2)->not->toBeGreaterThan(3)

I am learning php in the context of laravel so if this is a laravel only thing let me know.

I’ve done my due diligence and looked this up several times but I couldn’t find the answer I am looking for.

>Solution :

expect(2,2) might return an instance of Expectation class. The not is actually a method __get in PHP that returns an instance of the same or other class with some state marked as "negative assertion". toBeGreaterThan(3) is a method that uses to perform the assertion.
it’s the Expectation class:

(new Expectation(2))->not->toBeGreaterThan(3);

class Expectation {
    protected $negate = false;
    protected $value;

    public function __construct($value) {
        $this->value = $value;
    }

    public function __get($name) {
        if ($name === 'not') {
            $this->negate = true;
            return $this;
        }
    }

    public function toBeGreaterThan($limit) {
        if ($this->negate) {
            assert($this->value <= $limit, "Expected value not to be greater than $limit");
        } else {
            assert($this->value > $limit, "Expected value to be greater than $limit");
        }
    }
}

when you access $this->not, PHP will call the magic __get method with ‘not’ as its argument. Inside that method, you can decide what you want to return. In this case, it flips a "negate" flag and returns the same object.

Moreover, this is not a Laravel only thing. It’s a more general PHP pattern.