# Immutability in PHP Beyond readonly

DevFeed: [Immutability in PHP Beyond readonly](<https://devfeed.tech/articles/immutability-in-php-beyond-readonly-33295.md>)

Original publisher: [Read original article](<https://freek.dev/3181-immutability-in-php-beyond-readonly>)

Author: Freek Van der Herten (freek@spatie.be)

Published: 2026-08-17T12:12:30Z

Content type: article

Language: en

Sources: [freek.dev - all blogposts](<https://devfeed.tech/sources/freek-dev-all-blogposts.md>)

Topics: [PHP](<https://devfeed.tech/topics/php.md>)

Tags: [best-practices](<https://devfeed.tech/tags/best-practices.md>), [deep-dive](<https://devfeed.tech/tags/deep-dive.md>), [design-patterns](<https://devfeed.tech/tags/design-patterns.md>), [immutability](<https://devfeed.tech/tags/immutability.md>), [php](<https://devfeed.tech/tags/php.md>), [properties](<https://devfeed.tech/tags/properties.md>), [value](<https://devfeed.tech/tags/value.md>), [value-objects](<https://devfeed.tech/tags/value-objects.md>)

## AI overview

A deep dive into immutability in PHP, covering readonly properties, interior mutability, immutable value objects and collections, dates, cloning, boundaries, and testing.

## Source excerpt

A deep dive into immutability in PHP, from readonly properties and interior mutability to immutable value objects, collections, dates, cloning, boundaries, and testing. Read more