Adding dynamic properties by Registrars will be deprecated on PHP 8.2

[kenjis]

Registrars can add dynamic properties now.

But the sample code in the user guide will cause the error on PHP 8.2.
https://codeigniter4.github.io/CodeIgniter4/general/configuration.html#explicit-registrars

bash-3.2$ php public/index.php 


[ErrorException]

Creation of dynamic property Config\MySalesConfig::$actual is deprecated

at SYSTEMPATH/Config/BaseConfig.php:211

Backtrace:
  1    SYSTEMPATH/Config/BaseConfig.php:211
       CodeIgniter\Debug\Exceptions()->errorHandler(8192, 'Creation of dynamic property Config\\MySalesConfig::$actual is deprecated', '.../CodeIgniter4/system/Config/BaseConfig.php', 211)

  2    SYSTEMPATH/Config/BaseConfig.php:64
       CodeIgniter\Config\BaseConfig()->registerProperties()

  3    APPPATH/Controllers/Home.php:9
       CodeIgniter\Config\BaseConfig()->__construct()

  4    SYSTEMPATH/CodeIgniter.php:896
       App\Controllers\Home()->index()

  5    SYSTEMPATH/CodeIgniter.php:466
       CodeIgniter\CodeIgniter()->runController(Object(App\Controllers\Home))

  6    SYSTEMPATH/CodeIgniter.php:349
       CodeIgniter\CodeIgniter()->handleRequest(null, Object(Config\Cache), false)

  7    FCPATH/index.php:55
       CodeIgniter\CodeIgniter()->run()

bash-3.2$ php -v
PHP 8.2.0-dev (cli) (built: Jun 20 2022 00:32:41) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.2.0-dev, Copyright (c) Zend Technologies
    with Zend OPcache v8.2.0-dev, Copyright (c), by Zend Technologies

References:

• https://wiki.php.net/rfc/deprecate_dynamic_properties
• docs: fix Registrars explanation #6160

[iRedds]

#[AllowDynamicProperties]

[kenjis]

The issue is we will continue to use Dynamic Properties that PHP will denies by default or not.

[iRedds]

Why not use the Entity::$attributes case?

[kenjis]

Why not use the Entity::$attributes case?

What do you mean?
Do you mean that we should change it to use magic properties?

[kenjis]

I don't know the needs to add properties dynamically to Config objects.
I think dynamic properties are bad practice. So it will be rejected by default in PHP in the future.

We can override config properties by Registrars now. What's missing?

[iRedds]

What do you mean?
Do you mean that we should change it to use magic properties?

That is, all properties not previously defined should be placed in a separate container, which will have access through magic methods.

I'm just suggesting solutions to the problem in 8.2. This does not mean that I agree with the use of dynamic properties.

[kenjis]

@iRedds Okay, thanks for explanation. It is an option.

It seems there are three options.

1. Use #[AllowDynamicProperties]
2. Use magic properties
3. Do not support dynamic property injection

I think 3. is simple and preferable.

I did not know that Registrars can add dynamic properties.
Not documented until recently. See #6160

[kenjis]

See #6172 (comment)

[iRedds]

I do not know what to say.
The 8.2 conflicts you mentioned are mostly due to class design.

CodeIgniter4/system/Database/BaseConnection.php

Lines 336 to 340 in 053d669

	public function __construct(array $params)
	{
	foreach ($params as $key => $value) {
	$this->{$key} = $value;
	}

But the tests/_support/Config/Registrar.php class does not define a new property in the database configuration class.

[kenjis]

We do not recommend the use of dynamic properties in Registrar.