Render a partial from another Package in TYPO3 Flow / Fluid

RenderViewHelper.php

<?php
namespace Your\Package\ViewHelpers;

/*                                                                        *
 * This script belongs to the TYPO3 Flow package "TYPO3.Fluid".           *
 *                                                                        *
 * It is free software; you can redistribute it and/or modify it under    *
 * the terms of the GNU Lesser General Public License, either version 3   *
 * of the License, or (at your option) any later version.                 *
 *                                                                        *
 * The TYPO3 project - inspiring people to share!                         *
 *                                                                        */

use TYPO3\Flow\Mvc\Exception;
use TYPO3\Fluid\Core\ViewHelper\AbstractViewHelper;

/**
 * ViewHelper that renders a section or a specified partial
 *
 * == Examples ==
 *
 * <code title="Passing all variables to a partial">
 * <f:render partial="somePartial" arguments="{_all}" package="Your.Package" />
 * </code>
 * <output>
 * the content of the partial "somePartial".
 * Using the reserved keyword "_all", all available variables will be passed along to the partial
 * </output>
 *
 * @api
 */
class RenderViewHelper extends AbstractViewHelper {

	/**
	 * Renders the content.
	 *
	 * @param string $section Name of section to render. If used in a layout, renders a section of the main content file. If used inside a standard template, renders a section of the same file.
	 * @param string $partial Reference to a partial.
	 * @param array $arguments Arguments to pass to the partial.
	 * @param boolean $optional Set to TRUE, to ignore unknown sections, so the definition of a section inside a template can be optional for a layout
	 * @param string $package Package Key from which the partial should be rendered
	 * @return string
	 * @api
	 */
	public function render($section = NULL, $partial = NULL, $arguments = array(), $optional = FALSE, $package = NULL) {
		$arguments = $this->loadSettingsIntoArguments($arguments);
		if ($partial !== NULL) {
			if ($package !== NULL) {
				try {
					$partialRootpaths = $this->viewHelperVariableContainer->getView()->getOption('partialRootPaths');
					$this->viewHelperVariableContainer->getView()->setOption('partialRootPaths', array('resource://' . $package . '/Private/Partials'));
					$content = $this->viewHelperVariableContainer->getView()->renderPartial($partial, $section, $arguments);
					$this->viewHelperVariableContainer->getView()->setOption('partialRootPaths', $partialRootpaths);
					return $content;
				} catch(Exception $exception) {
					return $this->viewHelperVariableContainer->getView()->renderPartial($partial, $section, $arguments);
				}
			}
		} elseif ($section !== NULL) {
			return $this->viewHelperVariableContainer->getView()->renderSection($section, $arguments, $optional);
		}
		return '';
	}

	/**
	 * If $arguments['settings'] is not set, it is loaded from the TemplateVariableContainer (if it is available there).
	 *
	 * @param array $arguments
	 * @return array
	 */
	protected function loadSettingsIntoArguments($arguments) {
		if (!isset($arguments['settings']) && $this->templateVariableContainer->exists('settings')) {
			$arguments['settings'] = $this->templateVariableContainer->get('settings');
		}
		return $arguments;
	}
}

Template.html

{namespace yourPackage=Your\Package\ViewHelpers}
<yourPackage:render partial="partialName" package="Your.PackageWithThePartial" />