Lazyloading resources from the Zend Framework bootstrap

Bootstrap.php

<?php
/**
 * Example Zend Framework bootstrap with lazyloading of resources
 *
 * @author André Roaldseth <andrer@vg.no>
 */
class Bootstrap extends Zend_Application_Bootstrap_Bootstrap {
    /**
     * Creates a lazyloaded Memcached instance
     *
     * @return Memcached
     */
    public function _initMemcached() {
        return $this->lazyload(function() {
            return new Memcached();
        });
    }

    /**
     * Create a lazyloaded PDO instance.
     *
     * @return PDO
     */
    public function _initSomePDOClient() {
        $config = $this->getOption('pdo');

        return $this->lazyload(function() use ($config) {
            return new PDO($config['dsn']);
        });
    }

    /**
     * Retrieve a resource from the container.
     *
     * If the requested resource is a callable it will be exectued and the
     * result from the callable is returned instead of the callable itself.
     *
     * @see Zend_Application_Bootstrap_BootstrapAbstract::getResource()
     */
    public function getResource($name) {
        $resource = parent::getResource($name);

        if (is_callable($resource)) {
            return $resource();
        } else if ($resource !== null) {
            return $resource;
        }
    }

    /**
     * Method for creating closures which lazyload the resource.
     *
     * Creates an closure which will create the resource when called
     * and caches this resource so only one instance is created.
     *
     * @param callback $callable Callback which is able to create the resource.
     * @return mixed The instantiated resource, usually an object.
     */
    private function lazyload($callable) {
        return function () use ($callable) {
            static $object;

            if (is_null($object)) {
                $object = $callable();
            }

            return $object;
        };
    }
}

Wrote a blog post about how to use this lazy loading: http://tech.vg.no/2012/06/01/lazy-loading-resources-with-zend-framework-bootstrap/