A Template Engine in a Tweet

Template.php

<?php

/**
 * The render function is a lightweight template engine, that allows string
 * interpolation and output escaping.
 *
 * ...and it fits in a tweet.
 *
 * @author Quentin Schuler aka Sukei <qschuler@neosyne.com>
 */
function render($t,$a,$f='htmlentities') {
 return preg_replace_callback('/\${(\w+)}/',function($m)use($a,$f){return @$f($a[$m[1]]);},$t);
}

<?php

$view = render('Hello ${name}!', [
    'name' => 'sukei',
]);

echo $view; // Hello sukei!

<?php

$view = render('Hello ${name}!', [
    'name' => '<strong>sukei</strong>',
]);

echo $view; // Hello &lt;strong&gt;sukei&lt;/strong&gt;!

<?php

$view = render('Hello <strong>${name}</strong>!', [
    'name' => 'sukei',
]);

echo $view; // Hello <strong>sukei</strong>!

<?php

$view = render('Hello ${name}!', [
    'name' => '<strong>sukei</strong>',
], 'strip_tags');

echo $view; // Hello sukei!

<?php

$view = render('Hello ${name}!', []);

echo $view; // Hello !

<?php

$view = render('Hello ${name}!', [
    'name' => '<strong>sukei & neosyne</strong>',
], function($string) {
    return htmlentities(strip_tags($string));
});

echo $view; // Hello sukei &amp; neosyne!