PHP Manual: AllowDynamicProperties

Introduction

This attribute is used to mark classes that allow dynamic properties.

Note:
Although attributes themselves are not inherited, the effect of the AllowDynamicProperties attribute is inherited. Child classes of a class marked with this attribute will also allow dynamic properties, even if they do not explicitly declare the attribute.

Note:
This attribute was introduced in PHP 8.2.0 as the explicit way to allow dynamic properties. Creating a dynamic property on a class that does not use this attribute, and that does not implement __get() or __set(), is deprecated.

Class synopsis

#[\Attribute(\Attribute::TARGET_CLASS)]
final class AllowDynamicProperties {

/* Methods */

public function __construct()

}

Examples

Example #1 AllowDynamicProperties with a dynamic property

To enable dynamic properties, add #[\AllowDynamicProperties].

<?php
#[\AllowDynamicProperties]
class ValidExample { }

$obj = new ValidExample();
$obj->myDynamicProp = 1234;
?>

Example #2 AllowDynamicProperties with non-existing property

As of PHP 8.2.0, the declaration is required unless the class uses this attribute. Creating an undeclared property on such a class emits a deprecation notice.

<?php
class InvalidExample { }

$obj = new InvalidExample();
$obj->myUnknownProperty = 1234;
?>

Output of the above example in PHP 8.2:

Deprecated: Creation of dynamic property InvalidExample::$myUnknownProperty is deprecated in file on line 5

Example #3 AllowDynamicProperties with non-existing property in inherited class

<?php
class DefaultBehaviour { }

#[\AllowDynamicProperties]
class ClassAllowsDynamicProperties { }

class InheritedClassAllowsDynamicProperties extends ClassAllowsDynamicProperties { }

$o1 = new DefaultBehaviour();
$o2 = new InheritedClassAllowsDynamicProperties();

$o1->nonExistingProp = true;
$o2->nonExistingProp = true;
?>

Output of the above example in PHP 8.2:

Deprecated: Creation of dynamic property DefaultBehaviour::$nonExistingProp is deprecated in file on line 12

The AllowDynamicProperties attribute

Introduction

Class synopsis

Examples

See Also

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