Zend::loadInterface() works exactly the same as Zend::loadClass(), only it
loads an interface instead.
<?php loadInterface($interface, $dirs) ?>
The Zend::loadClass() method cannot be used for loading interfaces because the PHP
function class_exists() does cannot check
for interfaces (since PHP 5.0.2). Use Zend::loadInterface() instead.
If you ask for an interface with underscores in the name, and $dirs is null (the default),
Zend::loadInterface() will auto-discover the $dirs from the interface name
by converting underscores to directory separators. For example, if $interface is
Zend_Example_Interface, that will map to a path of Zend/Example/Interface.php.