minor #21067 [VarExporter] Remove LazyGhostTrait and LazyProxyTrait in favor of native lazy objects (alamirault)

This PR was merged into the 8.0 branch.

Discussion
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[VarExporter] Remove `LazyGhostTrait` and `LazyProxyTrait` in favor of native lazy objects

Fix #21059

Side question:

For 8.0 branch, what is the process for removing deprecations and versionadded ? Wait new issues from code repository and then remove remaining directives ?

Commits
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5d6c3a8 [VarExporter] Remove LazyGhostTrait and LazyProxyTrait in favor of native lazy objects

Author: javiereguiluz

components/var_exporter.rst

@@ -207,169 +207,5 @@ pattern, which also works with abstract classes, internal classes, and interface
 Use this mechanism only when native lazy objects cannot be leveraged
 (otherwise you'll get a deprecation notice).
 
-Legacy Creation of Lazy Objects
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-When using a PHP version earlier than 8.4, native lazy objects are not available.
-In these cases, the VarExporter component provides two traits that help you
-implement lazy-loading mechanisms in your classes.
-
-.. _var-exporter_ghost-objects:
-
-LazyGhostTrait
-..............
-
-.. deprecated:: 7.3
-
-    ``LazyGhostTrait`` is deprecated since Symfony 7.3. Use PHP 8.4's native lazy
-    objects instead. Note that using the trait with PHP versions earlier than 8.4
-    does not trigger a deprecation, to ease the transition.
-
-Ghost objects are empty objects, which see their properties populated the first
-time any method is called. Thanks to :class:`Symfony\\Component\\VarExporter\\LazyGhostTrait`,
-the implementation of the lazy mechanism is eased. The ``MyLazyObject::populateHash()``
-method will be called only when the object is actually used and needs to be
-initialized::
-
-    namespace App\Hash;
-
-    use Symfony\Component\VarExporter\LazyGhostTrait;
-
-    class HashProcessor
-    {
-        use LazyGhostTrait;
-
-        // This property may require a heavy computation to have its value
-        public readonly string $hash;
-
-        public function __construct()
-        {
-            self::createLazyGhost(initializer: $this->populateHash(...), instance: $this);
-        }
-
-        private function populateHash(array $data): void
-        {
-            // Compute $this->hash value with the passed data
-        }
-    }
-
-:class:`Symfony\\Component\\VarExporter\\LazyGhostTrait` also allows to
-convert non-lazy classes to lazy ones::
-
-    namespace App\Hash;
-
-    use Symfony\Component\VarExporter\LazyGhostTrait;
-
-    class HashProcessor
-    {
-        public readonly string $hash;
-
-        public function __construct(array $data)
-        {
-            $this->populateHash($data);
-        }
-
-        private function populateHash(array $data): void
-        {
-            // ...
-        }
-
-        public function validateHash(): bool
-        {
-            // ...
-        }
-    }
-
-    class LazyHashProcessor extends HashProcessor
-    {
-        use LazyGhostTrait;
-    }
-
-    $processor = LazyHashProcessor::createLazyGhost(initializer: function (HashProcessor $instance): void {
-        // Do any operation you need here: call setters, getters, methods to validate the hash, etc.
-        $data = /** Retrieve required data to compute the hash */;
-        $instance->__construct(...$data);
-        $instance->validateHash();
-    });
-
-While you never query ``$processor->hash`` value, heavy methods will never be
-triggered. But still, the ``$processor`` object exists and can be used in your
-code, passed to methods, functions, etc.
-
-Ghost objects unfortunately can't work with abstract classes or internal PHP
-classes. Nevertheless, the VarExporter component covers this need with the help
-of :ref:`Virtual Proxies <var-exporter_virtual-proxies>`.
-
-.. _var-exporter_virtual-proxies:
-
-LazyProxyTrait
-..............
-
-.. deprecated:: 7.3
-
-    ``LazyProxyTrait`` is deprecated since Symfony 7.3. Use PHP 8.4's native lazy
-    objects instead. Note that using the trait with PHP versions earlier than 8.4
-    does not trigger a deprecation, to ease the transition.
-
-The purpose of virtual proxies in the same one as
-:ref:`ghost objects <var-exporter_ghost-objects>`, but their internal behavior is
-totally different. Where ghost objects requires to extend a base class, virtual
-proxies take advantage of the **Liskov Substitution principle**. This principle
-describes that if two objects are implementing the same interface, you can swap
-between the different implementations without breaking your application. This is
-what virtual proxies take advantage of. To use virtual proxies, you may use
-:class:`Symfony\\Component\\VarExporter\\ProxyHelper` to generate proxy's class
-code::
-
-    namespace App\Hash;
-
-    use Symfony\Component\VarExporter\ProxyHelper;
-
-    interface ProcessorInterface
-    {
-        public function getHash(): bool;
-    }
-
-    abstract class AbstractProcessor implements ProcessorInterface
-    {
-        protected string $hash;
-
-        public function getHash(): bool
-        {
-            return $this->hash;
-        }
-    }
-
-    class HashProcessor extends AbstractProcessor
-    {
-        public function __construct(array $data)
-        {
-            $this->populateHash($data);
-        }
-
-        private function populateHash(array $data): void
-        {
-            // ...
-        }
-    }
-
-    $proxyCode = ProxyHelper::generateLazyProxy(new \ReflectionClass(AbstractProcessor::class));
-    // $proxyCode contains the actual proxy and the reference to LazyProxyTrait.
-    // In production env, this should be dumped into a file to avoid calling eval().
-    eval('class HashProcessorProxy'.$proxyCode);
-
-    $processor = HashProcessorProxy::createLazyProxy(initializer: function (): ProcessorInterface {
-        $data = /** Retrieve required data to compute the hash */;
-        $instance = new HashProcessor(...$data);
-
-        // Do any operation you need here: call setters, getters, methods to validate the hash, etc.
-
-        return $instance;
-    });
-
-Just like ghost objects, while you never query ``$processor->hash``, its value
-will not be computed. The main difference with ghost objects is that this time,
-a proxy of an abstract class was created. This also works with internal PHP class.
-
 .. _`OPcache`: https://www.php.net/opcache
 .. _`PSR-2`: https://www.php-fig.org/psr/psr-2/