I am experimenting with PHP namespacing within Worpdress plugins. The plugin includes a loader file which sets up the spl_autoload functionality and then instantiates a different controller depending on whether the current page request 'is_admin()' or not.


use lhes\system\controllers as sys;

set_include_path('./wp-content/plugins/lhes_experiment/' . PATH_SEPARATOR .     get_include_path());
spl_autoload_extensions(".php"); // comma-separated list
spl_autoload_register( 'spl_autoload' );

$config = array( ... );

if( is_admin() ){
   error_log( var_export( new sys\experiment( ), true ), 0 );
   error_log( var_export( new sys\experiment( ), true ), 0 );


namespace lhes\system\controllers;
   class experiment extends test{
      public $property;
      function __construct( ){
         $this->property = 'owls';


namespace lhes\system\controllers;
   class test{
      public $test;
      function __construct( ){
         $this->test = 'hi';

When the request is not and admin page, the code runs as expected and the error log shows:

[23-Jan-2013 12:55:27 UTC] lhes\system\controllers\experiment::__set_state(array(
   'property' => 'owls',
   'test' => 'hi',

However, when the request is to an admin page the exact same code does not work:

[23-Jan-2013 12:56:17 UTC] PHP Fatal error:  Class 'lhes\system\controllers\test' not found in C:\Program Files (x86)\Zend\Apache2\htdocs\wp-content\plugins\lhes_experiment\lhes\system\controllers\experiment.php on line 4

I've spent many an hour googling the problem but can't seem to find anything. If anyone has any ideas as to why this might be happening I would really appreciate some pointers.

1 Answer 1


Your set_include_path is wrong.

Instead use:


Tested it with your code and it works.

For reference: http://codex.wordpress.org/Determining_Plugin_and_Content_Directories

  • @mbadger: this is because your code is setting a relative path (relative to what? when?) whereas Wyck's code is setting an absolute path that will find your classes no matter from where is it called.
    – webaware
    Jan 24, 2013 at 9:35
  • @webaware: Thanks for pointing that out, setting the absolute path like Wyck pointed out did indeed sort the problem. I am curious as to why it worked at all though. My assumption was that it would treat '.' as the server root, which it appeared to do on the front end.
    – mbadger
    Jan 24, 2013 at 9:58
  • Every page / post on the front end effectively runs from the root of the website, as it is routed to {root}/index.php, whereas admin pages generally run from {root}/wp-admin (or from specific plugins' folders).
    – webaware
    Jan 24, 2013 at 10:03
  • Ah, of course! Much appreciated
    – mbadger
    Jan 24, 2013 at 10:12

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