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A trait that allows you to clone readonly properties in PHP 8.1

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This package provides a trait that allows you to clone objects with readonly properties in PHP 8.1. You can read an in-depth explanation as to why this is necessary here.

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You can install the package via composer:

composer require spatie/php-cloneable


In PHP 8.1, readonly properties aren't allowed to be overridden as soon as they are initialized. That also means that cloning an object and changing one of its readonly properties isn't allowed. It's likely that PHP will get some kind of clone with functionality in the future, but for now you can work around this issue by using this package.

class Post
    use Cloneable;

    public readonly string $title;
    public readonly string $author;

    public function __construct(string $title, string $author)
        $this->title = $title;
        $this->author = $author;

The Spatie\Cloneable\Cloneable adds a with method to whatever class you want to be cloneable, which you can pass one or more parameters. Note that you're required to use named arguments.

$postA = new Post(title: 'a', author: 'Brent');

$postB = $postA->with(title: 'b');
$postC = $postA->with(title: 'c', author: 'Freek');

A common practice would be to implement specific with* methods on the classes themselves:

class Post
    // …

    public function withTitle(string $title): self
        return $this->with(title: $title);

    public function withAuthor(string $author): self
        return $this->with(author: $author);


  • This package will skip calling the constructor when cloning an object, meaning any logic in the constructor won't be executed.
  • The with method will do a shallow clone, meaning that nested objects aren't cloned as well.


composer test


Please see CHANGELOG for more information on what has changed recently.


Please see CONTRIBUTING for details.

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The MIT License (MIT). Please see License File for more information.