Unsetting Properties Surprises

<?php

class X {
    public $a;
    public ?int $b = 1;

    function clean() {
        unset($this->a);
        unset($this->b);
    }
}

$x = new X;
$x->clean();

var_dump($x->a);
var_dump($x->b);

?>

Unsetting properties is always a surprise.

First, if the property was typed, it yields a Fatal Error, as the property cannot be accessed before initialization. And, the unset destroyed the property.

Also, checking an unset property with property_exists() is done against the class definition, not the current object state.

See Also

• Double quoted

• Unset Properties [Try me]

PHP Error Messages

• Undefined property

• Typed property %s::$%s must not be accessed before initialization

PHP Features

• unset

• property

Last updated: 14 July 2026