ReflectionException

    {
        if (isset($this->_reflections[$class])) {
            return [$this->_reflections[$class], $this->_dependencies[$class]];
        }
 
        $dependencies = [];
        $reflection = new ReflectionClass($class);
 
        $constructor = $reflection->getConstructor();
        if ($constructor !== null) {
            foreach ($constructor->getParameters() as $param) {
                if ($param->isDefaultValueAvailable()) {
                    $dependencies[] = $param->getDefaultValue();

     * @param array $config configurations to be applied to the new instance
     * @return object the newly created instance of the specified class
     */
    protected function build($class, $params, $config)
    {
        /* @var $reflection ReflectionClass */
        list ($reflection, $dependencies) = $this->getDependencies($class);
 
        foreach ($params as $index => $param) {
            $dependencies[$index] = $param;
        }
 
        $dependencies = $this->resolveDependencies($dependencies, $reflection);

    public function get($class, $params = [], $config = [])
    {
        if (isset($this->_singletons[$class])) {
            // singleton
            return $this->_singletons[$class];
        } elseif (!isset($this->_definitions[$class])) {
            return $this->build($class, $params, $config);
        }
 
        $definition = $this->_definitions[$class];
 
        if (is_callable($definition, true)) {
            $params = $this->resolveDependencies($this->mergeParams($class, $params));

     * @throws InvalidConfigException if the configuration is invalid.
     * @see \yii\di\Container
     */
    public static function createObject($type, array $params = [])
    {
        if (is_string($type)) {
            return static::$container->get($type, $params);
        } elseif (is_array($type) && isset($type['class'])) {
            $class = $type['class'];
            unset($type['class']);
            return static::$container->get($class, $params, $type);
        } elseif (is_callable($type, true)) {
            return call_user_func($type, $params);

        if (isset($this->_modules[$id])) {
            if ($this->_modules[$id] instanceof Module) {
                return $this->_modules[$id];
            } elseif ($load) {
                Yii::trace("Loading module: $id", __METHOD__);
                /* @var $module Module */
                $module = Yii::createObject($this->_modules[$id], [$id, $this]);
                $module->setInstance($module);
                return $this->_modules[$id] = $module;
            }
        }
 
        return null;

                }
            }
            if (isset($extension['bootstrap'])) {
                $component = Yii::createObject($extension['bootstrap']);
                if ($component instanceof BootstrapInterface) {
                    Yii::trace('Bootstrap with ' . get_class($component) . '::bootstrap()', __METHOD__);
                    $component->bootstrap($this);
                } else {
                    Yii::trace('Bootstrap with ' . get_class($component), __METHOD__);
                }
            }
        }
 

    protected function bootstrap()
    {
        $request = $this->getRequest();
        Yii::setAlias('@webroot', dirname($request->getScriptFile()));
        Yii::setAlias('@web', $request->getBaseUrl());
 
        parent::bootstrap();
    }
 
    /**
     * Handles the specified request.
     * @param Request $request the request to be handled
     * @return Response the resulting response

    /**
     * @inheritdoc
     */
    public function init()
    {
        $this->state = self::STATE_INIT;
        $this->bootstrap();
    }
 
    /**
     * Initializes extensions and executes bootstrap components.
     * This method is called by [[init()]] after the application has been fully configured.
     * If you override this method, make sure you also call the parent implementation.

     */
    public function __construct($config = [])
    {
        if (!empty($config)) {
            Yii::configure($this, $config);
        }
        $this->init();
    }
 
    /**
     * Initializes the object.
     * This method is invoked at the end of the constructor after the object is initialized with the
     * given configuration.

        $this->state = self::STATE_BEGIN;
 
        $this->preInit($config);
 
        $this->registerErrorHandler($config);
 
        Component::__construct($config);
    }
 
    /**
     * Pre-initializes the application.
     * This method is called at the beginning of the application constructor.
     * It initializes several important application properties.