Symfony VarExporter Component (7.4)

Overview

The VarExporter component exports any serializable PHP data structure to plain PHP code and allows instantiation and population of objects without calling their constructors. It provides significant performance benefits through OPcache optimization.

Quick Reference

Installation

bash

composer require symfony/var-exporter

VarExporter::export()

Export PHP data structures to plain PHP code:

php

use Symfony\Component\VarExporter\VarExporter;

$exported = VarExporter::export($someVariable);
file_put_contents('exported.php', '<?php return '.$exported.';');

// Regenerate the variable later
$regeneratedVariable = require 'exported.php';

Instantiator

Create objects without calling constructors:

php

use Symfony\Component\VarExporter\Instantiator;

// Create empty instance
$object = Instantiator::instantiate(Foo::class);

// Create with properties
$object = Instantiator::instantiate(Foo::class, ['propertyName' => $value]);

// Set parent class private properties
$object = Instantiator::instantiate(Foo::class, [], [
    ParentClass::class => ['privateProperty' => $value],
]);

Hydrator

Populate properties of existing objects:

php

use Symfony\Component\VarExporter\Hydrator;

$object = new Foo();
Hydrator::hydrate($object, ['propertyName' => $value]);

// Populate parent class private properties
Hydrator::hydrate($object, [], [
    ParentClass::class => ['privateProperty' => $value],
]);

Lazy Objects (PHP 8.4+)

Create lazy proxies for deferred initialization:

php

use Symfony\Component\VarExporter\ProxyHelper;

$proxyCode = ProxyHelper::generateLazyProxy(new \ReflectionClass(SomeInterface::class));
eval('class ProxyDecorator'.$proxyCode);

$proxy = ProxyDecorator::createLazyProxy(initializer: function (): SomeInterface {
    return new SomeHeavyClass(...$dependencies);
});

Legacy: LazyGhostTrait (Deprecated in 7.3)

php

use Symfony\Component\VarExporter\LazyGhostTrait;

class LazyProcessor extends Processor {
    use LazyGhostTrait;
}

$processor = LazyProcessor::createLazyGhost(initializer: function (Processor $instance): void {
    $instance->__construct($data);
});

Legacy: LazyProxyTrait (Deprecated in 7.3)

php

use Symfony\Component\VarExporter\ProxyHelper;

$proxyCode = ProxyHelper::generateLazyProxy(new \ReflectionClass(AbstractProcessor::class));
eval('class ProcessorProxy'.$proxyCode);

$processor = ProcessorProxy::createLazyProxy(initializer: function (): ProcessorInterface {
    return new ConcreteProcessor($data);
});

Key Advantages

Feature	VarExporter	serialize()	var_export()
OPcache Performance	Yes	No	No
Preserves __wakeup/__sleep	Yes	Yes	No
Reference Handling	Yes	Yes	Limited
PSR-2 Format	Yes	No	Partial

Full Documentation

•Docs: https://symfony.com/doc/7.4/components/var_exporter.html
•GitHub: https://github.com/symfony/var-exporter

For complete API documentation and advanced usage, see references/var-exporter.md.