PHP 8.2 Readonly classes

PHP 8.2 was released in November 2021 and brought several new features and improvements to the popular programming language. One of the most notable additions is the introduction of Readonly classes, which offer developers a new way to ensure that class properties cannot be modified after initialization.

In object-oriented programming, it is common to define class properties and then modify them as needed throughout the life of an object. However, in some cases, it may be desirable to prevent the modification of certain properties after they have been initialized. This is where Readonly classes come in.

A Readonly class is a new type of class in PHP 8.2 that allows developers to define properties that cannot be modified after they have been initialized. Once a property is set, it cannot be changed, ensuring that the value remains the same throughout the life of the object.

To define a Readonly class in PHP 8.2, developers can use the new readonly keyword when declaring properties. For example:

class Person {
   public readonly string $name;
   public readonly int $age;

   public function __construct(string $name, int $age) {
      $this->name = $name;
      $this->age = $age;

In this example, the name and age properties are defined as Readonly, meaning they cannot be modified after they are initialized in the constructor.

One of the main benefits of Readonly classes is that they can help improve code quality and reduce the risk of bugs. By preventing properties from being modified after initialization, Readonly classes can help ensure that the object remains in a valid state throughout its life, reducing the likelihood of unexpected behavior or errors.

In addition to Readonly classes, PHP 8.2 also introduced other new features and improvements, such as improved error messages, new array unpacking syntax, and enhancements to the type system.

Overall, Readonly classes are a welcome addition to PHP 8.2 and offer developers a powerful new tool for improving code quality and reducing the risk of bugs. If you’re working with PHP 8.2 or later, be sure to consider using Readonly classes in your object-oriented code.