Is a property default value of null the same as no default value?

Question

And can I therefore safely refactor all instances of

class Blah
{
    // ...
    private $foo = null;
    // ...
}

to

class         


        

Answer 1

Apart from the accepted answer that is still true, with the addition of typed properties in PHP 7.4 there are new things to consider.

Given the following code

class A {
    public ?DateTime $date;
}

$a = new A();
$a->date;

You will get the error

PHP Fatal error:  Uncaught Error: Typed property A::$date must not be accessed before initialization

That means that the property $date is not automatically initialized with null even though this would be a valid value. You'll have to initialize it directly like public ?DateTime $date = null; or use the constructor to do so.