Zend Framework

// in your bootstrap (needed so helper is present at preDispatch()):
Zend_Controller_Action_HelperBroker::addHelper(new Zend_Controller_Action_Helper_View());

// and a controller class, foo module:
class Foo_BarController extends Zend_Controller_Action
{
    // renders bar/index.phtml by default; no action required
    public function indexAction()
    {
    }

    // render bar/form.phtml instead of bar/baz.phtml
    public function bazAction()
    {
        $this->_helper->view('form');
    }

    // don't render anything
    public function hideAction()
    {
        $this->_helper->view->noRender();
    }

    // renders bar/populate.phtml with variable 'foo' set to 'bar'
    public function populateAction()
    {
        $this->view->foo = 'bar';
    }
}

// in one of your view scripts:
<?php $this->foo(); // call Foo_Bar_View_Helper_Foo::foo() ?>

<?php
class Zend_Controller_Action_Helper_View extends Zend_Controller_Action_Helper_Abstract
{
    /**
     * @var Zend_View_Interface
     */
    public $view;

    /**
     * Front controller instance
     * @var Zend_Controller_Front
     */
    protected $_frontController;

    /**
     * Whether or not to use a controller name as a subdirectory when rendering
     * @var boolean
     */
    protected $_noController    = false;

    /**
     * Whether or not to autorender postDispatch
     * @var boolean
     */
    protected $_noRender        = false;

    /**
     * Which named segment of the response to utilize
     * @var string
     */
    protected $_responseSegment = null;

    /**
     * Which action view script to render
     * @var string
     */
    protected $_scriptAction    = null;

    /**
     * View script suffix
     * @var string
     */
    protected $_viewSuffix      = 'phtml';

    public function setView(Zend_View_Interface $view)
    {
        $this->view = $view;
    }

    /**
     * Retrieve front controller instance
     * 
     * @return Zend_Controller_Front
     */
    public function getFrontController()
    {
        if (null === $this->_frontController) {
            $this->_frontController = Zend_Controller_Front::getInstance();
        }

        return $this->_frontController;
    }

    protected function _generateDefaultPrefix()
    {
        if (null === $this->_actionController) {
            return 'Zend_View_Helper';
        }

        $class = get_class($this->_actionController);

        if (!strstr($class, '_')) {
            $prefix = 'Zend_View_Helper';
        } else {
            $prefix = substr($class, 0, strpos($class, '_')) . '_View_Helper';
        }

        return $prefix;
    }

    /**
     * Retrieve base path based on location of 
     * 
     * @return void
     */
    protected function _getBasePath()
    {
        if (null === $this->_actionController) {
            return '.' . DIRECTORY_SEPARATOR . 'views';
        }

        $front      = $this->getFrontController();
        $modulePath = $front->getControllerDirectory($this->getRequest()->getModuleName());
        if (null === $modulePath) {
            throw new Zend_Controller_Action_Exception('Cannot determine view base path: invalid module "' . $module . '"in request');

        }
        $path = realpath($modulePath . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . 'views');
        return $path;
    }

    /**
     * Initialize the view object
     *
     * $options may contain the following keys:
     * - noController - flag indicating whether or not to look for view scripts in subdirectories named after the controller
     * - noRender - flag indicating whether or not to autorender postDispatch()
     * - responseSegment - which named response segment to render a view script to
     * - scriptAction - what action script to render
     * - viewSuffix - what view script filename suffix to use
     * 
     * @param  string $path 
     * @param  string $prefix 
     * @param  array $options 
     * @return void
     */
    public function initView($path = null, $prefix = null, array $options = array())
    {
        if (null === $this->view) {
            $this->setView(new Zend_View());
        }

        if (null === $path) {
            $path = $this->_getBasePath();
        }

        if (null === $prefix) {
            $prefix = $this->_generateDefaultPrefix();
        }

        $this->view->addBasePath($path, $prefix);

        $this->_noRender        = false;
        $this->_responseSegment = null;
        $this->_scriptAction    = null;

        foreach ($options as $key => $value)
        {
            switch ($key) {
                case 'noController':
                case 'noRender':
                    $property = '_' . $key;
                    $this->{$property} = ($value) ? true : false;
                    break;
                case 'responseSegment':
                case 'scriptAction':
                case 'viewSuffix':
                    $property = '_' . $key;
                    $this->{$property} = (string) $value;
                    break;
                default:
                    break;
            }
        }

        if ((null !== $this->_actionController) && (null === $this->_actionController->view)) {
            $this->_actionController->view       = $this->view;
            $this->_actionController->viewSuffix = $this->_viewSuffix;
        }
    }

    /**
     * preDispatch - initialize view
     * 
     * @return void
     */
    public function preDispatch()
    {
        $this->initView();
    }

    /**
     * Set the noRender flag (i.e., whether or not to autorender)
     * 
     * @param  boolean $flag 
     * @return Wopnet_Controller_Helper_View
     */
    public function setNoRender($flag = true)
    {
        $this->_noRender = ($flag) ? true : false;
        return $this;
    }

    /**
     * Retrieve noRender flag value
     * 
     * @return boolean
     */
    public function getNoRender()
    {
        return $this->_noRender;
    }

    /**
     * Set the view script to use
     * 
     * @param  string $name 
     * @return Wopnet_Controller_Helper_View
     */
    public function setScriptAction($name)
    {
        $this->_scriptAction = (string) $name;
        return $this;
    }

    /**
     * Retrieve view script name
     * 
     * @return string
     */
    public function getScriptAction()
    {
        return $this->_scriptAction;
    }

    /**
     * Set the response segment name
     * 
     * @param  string $name 
     * @return Wopnet_Controller_Helper_View
     */
    public function setResponseSegment($name)
    {
        $this->_responseSegment = (string) $name;
        return $this;
    }

    /**
     * Retrieve named response segment name
     * 
     * @return string
     */
    public function getResponseSegment()
    {
        return $this->_responseSegment;
    }

    /**
     * Set the noController flag (i.e., whether or not to render into controller subdirectories)
     * 
     * @param  boolean $flag 
     * @return Wopnet_Controller_Helper_View
     */
    public function setNoController($flag = true)
    {
        $this->_noController = ($flag) ? true : false;
        return $this;
    }

    /**
     * Retrieve noController flag value
     * 
     * @return boolean
     */
    public function getNoController()
    {
        return $this->_noController;
    }

    /**
     * Set options for rendering a view script
     * 
     * @param  string $action View script to render
     * @param  string $name Response named segment to render to
     * @param  boolean $noController Whether or not to render within a subdirectory named after the controller
     * @return Wopnet_Controller_Helper_View
     */
    public function setRender($action = null, $name = null, $noController = false)
    {
        $this->_scriptAction    = (string) $action;
        $this->_responseSegment = (string) $name;
        $this->_noController    = ($noController) ? true : false;

        return $this;
    }

    /**
     * postDispatch - auto render a view
     *
     * Only autorenders if: 
     * - _noRender is false
     * - action controller is present
     * - request has not been re-dispatched (i.e., _forward() has not been called)
     * 
     * @return void
     */
    public function postDispatch()
    {
        if (!$this->_noRender 
            && (null !== $this->_actionController)
            && $this->getRequest()->isDispatched())
        {
            $this->_actionController->render($this->_scriptAction, $this->_responseSegment, $this->_noController);
        }
    }

    /**
     * Use this helper as a method; proxies to setRender()
     * 
     * @param  string $action 
     * @param  string $name 
     * @param  boolean $noController 
     * @return void
     */
    public function direct($action = null, $name = null, $noController = false)
    {
        $this->setRender($action, $name, $noController);
    }
}