Clarify what to do with Serializable interface

[LeoZandvliet]

Affected page

https://www.php.net/manual/en/class.serializable.php

Current issue

First time in years I had to write a class that would be serialized for caching.
So created a class implementing Serializable, functions serialize and unserialize(string $data) are automatically created, but also deprecated messages about not implementing __serialize and __unserialize(array $data).
Looking up Interface Serializable on what to do and the difference between the methods. The example looks outdated to me, so dig further. Finally found this RFC: Phasing out Serializable.

Suggested improvement

Would it align with the phasing out path to add a second warning/alert on that Interface Serializable page:

Note: if you have to support php < v8.1, implement all of these: __serialize(), serialize(), __unserialize(), unserialize(). If supporting only >= 8.1, implement only the magic functions __serialize() and __unserialize().

And/or add a reference to the RFC Phasing out Serializable

Additional context (optional)

If using ONLY the magic methods,
Is there an alternative for $someObject instanceof Serializable ?
For example: https://onlinephp.io/c/c7ecd