Imagine (or any namespaced library) in symfony 1.4

imaginesf14.php

<?php 

// in the top of config/projectconfiguration.php you should have
require_once dirname(__FILE__).'/../lib/vendor/symfony/lib/autoload/sfCoreAutoload.class.php';
sfCoreAutoload::register();

// Immediately beneath, add this:
require_once dirname(__FILE__).'/../lib/util/NsAutoload.class.php';

// then within ProjectConfiguration::setup() add:
$this->dispatcher->connect('context.load_factories', (array('NsAutoload', 'register')));

// I've forgotten why, but it didn't work properly if I called NsAutoLoad::register directly 
// after including the file, like the sfCore one is

?>

<?php
// then this is the contents of NsAutoload.class.php, which you can put wherever you like - just change the include above to point to it

class NsAutoload {

  public static function register() {
    spl_autoload_register(array('NsAutoload', 'autoload'), false);
  }

  public static function autoload($class) {
    $timer = sfTimerManager::getTimer('NsAutoload');
    $namespaces = array("Imagine" => 'Imagine/lib/'); // edit this to support other libs, or you could extend it to be handled by a config handler and a yml file if you've loads
    if (!strpos($class, "\\")) {
      $timer->addTime();
      return;
    }

    foreach ($namespaces as $space=>$path) {
      if (strpos($class, $space)===0) {
        // i put imagine within lib/vendor, amend here if you do something different.
        require_once(sfConfig::get('sf_lib_dir') . '/vendor/' . $path . str_replace('\\', '/', $class) . '.php');
      }
    }

    $timer->addTime();
  }

}