Object Oriented Snippets for MODX :D There are a couple of files here. The first one (`1_interface_and_base_class.php`) contains an interface and the base abstract class for creating snippets. The second file (`2_example_snippet.php`) is a real basic example of a snippet. The third file (`3_modSnippet.php`) is the code that is in the actual modS…

1_interface_and_base_class.php

<?php

namespace mhwd\Donations;

/**
 * Interface ObjectOrientedSnippet
 *
 * @see Snippet class
 *
 * @package mhwd\Donations
 */
interface ObjectOrientedSnippet {
    public function __construct(\modX $modx, array $properties = array());
    public function execute();
    public function getDefaultProperties();
    public function getProperties();
    public function getProperty($key, $default = null);
}

/**
 * Class Snippet
 *
 * Base implementation of the ObjectOrientedSnippet interface. Implement the execute() method.
 *
 * @package mhwd\Donations
 */
abstract class Snippet implements ObjectOrientedSnippet {
    protected $modx;
    protected $properties = array();

    /**
     * Creates a new ObjectOrientedSnippet instance, setting $modx to the internal $this->modx and setting
     * properties to $this->properties.
     *
     * @param \modX $modx
     * @param array $properties
     */
    public function __construct(\modX $modx, array $properties = array())
    {
        $this->modx =& $modx;
        $this->properties = array_merge($this->getDefaultProperties(), $properties);
    }

    /**
     * Returns an array of each property passed to the snippet.
     *
     * @return array
     */
    public function getProperties()
    {
        return $this->properties;
    }

    /**
     * Grabs a specific property and returns its value, or the default value.
     *
     * @param $key
     * @param null $default
     * @return mixed
     */
    public function getProperty($key, $default = null)
    {
        if (isset($this->properties[$key])) {
            return $this->properties[$key];
        }
        return $default;
    }
}

2_example_snippet.php

<?php

namespace mhwd\Donations;

class DonationsSnippet extends Snippet {

    /**
     * Executes the snippet and returns the result (string).
     *
     * @return string
     */
    public function execute()
    {
        return 'Whoohee! It works! ' . print_r($this->getProperties(), true);
    }

    /**
     * Returns an array of default properties for the snippet.
     *
     * @return array
     */
    public function getDefaultProperties()
    {
        return array(
            'foo' => 'bar'
        );
    }
}

3_modSnippet.php

<?php
/**
 * @var modX $modx
 * @var Donations $donations
 * @var array $scriptProperties
 */

$modelPath = $modx->getOption('donations.core_path', null, MODX_CORE_PATH . 'components/donations/') . 'model/donations/';
$donations = $modx->getService('donations', 'Donations', $modelPath);
if (!$donations || !($donations instanceof Donations)) {
    $modx->log(modX::LOG_LEVEL_ERROR, '[Donations] Could not load Donations service class from ' . $modelPath);
    return '<p class="error">Sorry, donations are currently unavailable.</p>';
}

return $donations->runSnippet('Donations', $scriptProperties);

4_donations_runSnippet.php

<?php

class Donations
{
    /** @var modX $modx */
    public $modx;
    public $config = array();
    public $debug = 0;

    /**
     * Creates a new Donations instance.
     *
     * @param \modX $modx
     * @param array $config
     */
    function __construct(\modX &$modx, array $config = array())
    {
        $this->modx =& $modx;

        $corePath = $this->modx->getOption(
            'donations.core_path',
            $config,
            $this->modx->getOption('core_path') . 'components/donations/'
        );
        $assetsUrl = $this->modx->getOption(
            'donations.assets_url',
            $config,
            $this->modx->getOption('assets_url') . 'components/donations/'
        );
        $assetsPath = $this->modx->getOption(
            'donations.assets_path',
            $config,
            $this->modx->getOption('assets_path') . 'components/donations/'
        );
        $this->config = array_merge(
            array(
                'basePath' => $corePath,
                'corePath' => $corePath,
                'modelPath' => $corePath . 'model/',
                'controllersPath' => $corePath . 'controllers/',
                'processorsPath' => $corePath . 'processors/',
                'elementsPath' => $corePath . 'elements/',
                'templatesPath' => $corePath . 'templates/',
                'assetsPath' => $assetsPath,
                'jsUrl' => $assetsUrl . 'js/',
                'cssUrl' => $assetsUrl . 'css/',
                'assetsUrl' => $assetsUrl,
                'connectorUrl' => $assetsUrl . 'connector.php',
            ),
            $config
        );

        $this->modx->lexicon->load('donations:default');
    }

    public function runSnippet($snippet, array $properties = array())
    {
        if (!class_exists('Snippet')) {
            require_once dirname(__FILE__) . '/Snippet.php';
        }

        $fqn = '\mhwd\Donations\\' . ucfirst($snippet) . 'Snippet';
        $file = $this->config['modelPath'] . 'donations/' . ucfirst($snippet) . 'Snippet.php';
        if (file_exists($file)) {
            require_once $file;
        }

        if (class_exists($fqn)) {
            $snippet = new $fqn($this->modx, $properties);
            if ($snippet instanceof \mhwd\Donations\ObjectOrientedSnippet) {
                return $snippet->execute();
            }
        }
        return 'Snippet ' . $snippet . ' not found :(';

    }

}