src/Serializer.php
public static function wrapClosures(&$data, SerializerInterface $serializer)
    {
        if ($data instanceof \Closure) {
            // Handle and wrap closure objects.
            $reflection = new \ReflectionFunction($data);
            if ($binding = $reflection->getClosureThis()) {
                self::wrapClosures($binding, $serializer);
                $scope = $reflection->getClosureScopeClass();
                $scope = $scope ? $scope->getName() : 'static';
                $data = $data->bindTo($binding, $scope);
            }
            $data = new SerializableClosure($data, $serializer);
        } elseif (is_array($data) || $data instanceof \stdClass || $data instanceof \Traversable) {
            // Handle members of traversable values.
            foreach ($data as &$value) {
                self::wrapClosures($value, $serializer);
            }
        } elseif (is_object($data) && !$data instanceof \Serializable) {
            // Handle objects that are not already explicitly serializable.
            $reflection = new \ReflectionObject($data);
            if (!$reflection->hasMethod('__sleep')) {
                foreach ($reflection->getProperties() as $property) {
                    if ($property->isPrivate() || $property->isProtected()) {
                        $property->setAccessible(true);
                    }
                    $value = $property->getValue($data);
                    self::wrapClosures($value, $serializer);
                    $property->setValue($data, $value);
                }
            }
        }
    }
public static function wrapClosures(&$data, SerializerInterface $serializer)
    {
        if ($data instanceof \Closure) {
            // Handle and wrap closure objects.
            $reflection = new \ReflectionFunction($data);
            if ($binding = $reflection->getClosureThis()) {
                self::wrapClosures($binding, $serializer);
                $scope = $reflection->getClosureScopeClass();
                $scope = $scope ? $scope->getName() : 'static';
                $data = $data->bindTo($binding, $scope);
            }
            $data = new SerializableClosure($data, $serializer);
        } elseif (is_array($data) || $data instanceof \stdClass || $data instanceof \Traversable) {
            // Handle members of traversable values.
            foreach ($data as &$value) {
                self::wrapClosures($value, $serializer);
            }
        } elseif (is_object($data) && !$data instanceof \Serializable) {
            // Handle objects that are not already explicitly serializable.
            $reflection = new \ReflectionObject($data);
            if (!$reflection->hasMethod('__sleep')) {
                foreach ($reflection->getProperties() as $property) {
                    if ($property->isPrivate() || $property->isProtected()) {
                        $property->setAccessible(true);
                    }
                    $value = $property->getValue($data);
                    self::wrapClosures($value, $serializer);
                    $property->setValue($data, $value);
                }
            }
        }
    }
Recursively traverses and wraps all Closure objects within the value.

NOTE: THIS MAY NOT WORK IN ALL USE CASES, SO USE AT YOUR OWN RISK.

@param mixed $data Any variable that contains closures.
@param SerializerInterface $serializer The serializer to use.