Only Initialize With Short Assignation Coalesce¶

<?php

class x {
    private static self $x;

    static function getInstance() {
        // all good
        return self::$x ??= new self();
    }

    static function getInstance2() {
        // Not ok : cannot access before initialisation
        return self::$x = self::$x ?? new self();
    }

    static function getError() {
        // Not ok : cannot access before initialisation
        if (!self::$x instanceof self) {
            self::$x = new self();
        }

        return self::$x;
    }
}

It is not possible to access a property before its initialisation. This is true to both static and normal properties.

While normal properties are initialized at constructor time, static properties might require a check before assignation : in case the property has not been yet assigned, a Fatal error will stop the code execution.

In fact, there is a way : it is the short assignation with coalesce, which will accept to check the NULL value, and only fill it if it is null.

See Also¶

Properties
this function never returns [Try me]

PHP Features¶

Last updated: 14 July 2026