Allows backward compatible support for the new __serialize and __unserialize methods

[goetas]

Allows backward compatible support for the new __serialize and __unserialize methods and plan upgrade path to remove the \Serialize interface in 3.0.

This pull request introduces two new methods serializeToArray and unserializeFromArray to handle in a backward compatible way (php 8.1) the serialization process.

If you were extending the metadata classes, you custom serialization methods were looking probably as something as this:

class MyMetadata extends PropertyMetadata 
{
    // ... more code
    public function serialize()
    {
        $data = parent::serialize();

        return \serialize([$data, $this->moreCustomMetadataProps]);
    }

    public function unserialize($data)
    {
        list($data, $this->moreCustomMetadataProps) = \unserialize($data);

        parent::unserialize($data);
    }
}

After this change, your code should look like this:

class MyMetadata extends PropertyMetadata 
{
    // ... more code
    protected function serializeToArray(): array
    {
        $data = parent::serializeToArray();

        return [$data, $this->moreCustomMetadataProps];
    }

    protected function unserializeFromArray(array $data): void
    {
        list($data, $this->moreCustomMetadataProps) = $data;

        parent::unserializeFromArray($data);
    }
}

Note, this is something you should change only if you plan to upgrade to the upcoming 3.0 version of this package (and plan support for php 9).

[alexander-schranz]

You got a typo in the example in the PR description:

-    protected function serializeToArray():
+    protected function serializeToArray(): array
    {
-        $data = parent::serializeToArray(): array
+        $data = parent::serializeToArray();

Thx for adding this, it makes it easier for us to keep it backward compatible!