A PHP function to create an <a> link and a callback to join HTML tag attributes.

a.php

<?php
function a($href, $text=NULL, $attributes=NULL) {
    if (!isset($text))
        $text = strpos((string)$href, 'mailto:') !== FALSE ? substr($href, 7) : $href;
    $attributes = compact('href') + (array)$attributes;
    return sprintf('<a%s>%s</a>', join_attributes($attributes), (string)$text);
}
function join_attributes($attributes) {
    $attrs = array();
    foreach ((array)$attributes as $key => $value)
        if ($key === 'value' || !is_blank($value))
            $attrs []= sprintf(' %s="%s"', $key, (string)$value);
    return join($attrs);
}
function is_blank($value) {
    return empty($value) && !is_numeric($value);
}

aTest.php

<?php
a('http://google.com', 'Google', array('title'=>'Search with Google', 'class'=>'no_underline'));
// => &lt;a href="http://google.com" title="Search with Google" class="no_underline"&gt;Google&lt;/a&gt;