get_object_vars() does not return null, because those values are not null. These properties have not been initialized -- essentially they do not exist.

If you wish to get all the properties that were *declared* in the class, regardless of whether they have been initialized or unset, you can use ReflectionObject.

I understand that those properties have never been initialized, however, in previous PHP versions, those properties would still be visible in the array returned by get_object_vars. Is this an undocumented change then? Because the documentation for get_object_vars still suggests that it should be returning NULL for unassigned properties: "If a property has not been assigned a value, it will be returned with a NULL value."

I also noticed that the behaviour seems inconsistent with get_class_vars now, as that function still returns the expected array, with the difference being that get_class_vars returns the initial values instead of the current values.

An example: https://3v4l.org/fFpe4

> I understand that those properties have never been initialized, however, in previous PHP versions, those properties would still be visible in the array returned by get_object_vars. Is this an undocumented change then?

No. The behavior is exactly the same as in previous PHP versions: Properties that have a value are included, properties that are unset are not. The only difference is that typed properties start out in an uninitialized state, while untyped properties start with a null default value. If you wish the default value to be null, please add an explicit "= null" initializer. (Though of course I would not recommend doing so without good reason.)

> Because the documentation for get_object_vars still suggests that it should be returning NULL for unassigned properties: "If a property has not been assigned a value, it will be returned with a NULL value."

You are correct that the phrasing in the get_object_vars() documentation is wrong. The sentence "If a property has not been assigned a value, it will be returned with a NULL value" should be removed without replacement. I'm reclassifying this as a documentation issue.

> in previous PHP versions, those properties would still 
> be visible in the array returned by get_object_vars

don't match

> not returning typed empty properties

becaus ein previous versions they couldn't be typed

I see! Thanks for clarifying, I didn't know that typed properties would behave differently like that.

So for future reference:

public $foo; is the same as public $foo = null; but it is not the same as doing public ?string $foo;

> public $foo; is the same as public $foo = null; but it is not
> the same as doing public ?string $foo;

Yes.