<h1>Filters</h1>
<h2>Single filter</h2>
<pre><code>
<?php
require 'h2o/h2o.php';
$user = array('name'=>'peter', 'email'=> 'someone@gmail.com');
echo h2o('{{ user.email | avator | image_tag')->render(compact('user'));
?>
h2o::addFilter('avator');
function avator($email) {
return "http://gravator.com/api?email=".md5($email);
}
?>
</code></pre>
<h2>Filter collections</h2>
<p>If you have a lot of related filters for your application, putting them into a filter collection class can give you better encapsulation and reuse on your methods.</p>
<p>Here is some code example of a Filter collection class, h2o::addFilter() is a static method overloading a few different parameter options, if you pass-in a filter collection then all class methods will become h2o filters.</p>
<pre><code>
<?php
h2o::addFilter('HtmlFilters');
class HtmlFilters extends FilterCollection {
function base_url($url) {
return $url;
}
function script_tag($path) {
return sprintf('<script type="text/javascript" src="%s.js">', self::base_url($path));
}
...
}
?>
</code></pre>
<h1>Tags</h1>
<p>Tags are powerful stuff, creating a new tag allows you to</p>
<ul>
<li>interact with h2o context and parser objects</li>
<li>implement new language construct, template macros</li>
<li>consuming external resources</li>
</ul>
<p>This is favorite example of implementing a rss feed loader tag less than 20 lines with object caching</p>
<pre><code>
<?php
require 'h2o/h2o.php'
h2o::addTag('load_feed_items');
class Load_feed_items_Tag extends H2o_Node {
var $url, $cacheKey;
function __construct($argstring, $parser, $pos=0) {
$this->url = trim($argstring);
$this->cacheKey = md5($this->url);
}
function render($context, $stream) {
$cache = h2o_cache($context->options);
# try cached
if (! ($feed = $cache->read($this->key))) {
$feed = file_get_contents($this->url);
$cache->write($this->key, $feed);
}
$feed = simplexml_load_string($feed)->xpath('//channel/item');
$context->set('feed_items', $feed);
}
}
# Template part
$tpl = <<<TPL
{% load_feed_items http://feeds.digg.com/digg/popular.rss %}
{% for item in feed_items %}
{{ item.title | links_to item.url }}
{% endfor %}
TPL;
echo h2o($tpl)->render();
</code></pre>
<h1>Extensions</h1>
2010-02-09T19:11:52-08:00
119751
extending-h2o
11784
Extending H2o
2009-04-07T03:31:40-07:00
70642