Where to put third party PHP library?

4 comments

1. If each plugin/theme functions on its own, then you should probably drop the the library in every theme/plugin.

   Then just check to see if it a class or function from the third-party library exists before requiring it.

   <?php
   if( class_exists( 'SomeClass' ) )
   {
       // require/include here
   }
   

   or

   <?php
   if( function_exists( 'some_function' ) )
   {
      // Require/include stuff here
   }
   

   Alternatively, you could wrap every function/class/variable/constant from the third party library in a check to see if it exists, like pluggable functions.

   If all of the plugins and the theme are dependent on one another, then it doesn’t really make much sense to divide them up and you should probably rethink that.

   Log in to Reply

2. Bind all depended code to an action in the library plugin.

   Sample code for the library plugin:

   add_action( 'plugins_loaded', 'load_library', 0 );
   
   function load_library()
   {
       # load all the classes and files you need
       # Set up $plugin_url and $plugin_directory
   
       do_action( 'library_loaded', $plugin_url, $plugin_directory );
   }
   

   In your depended code do nothing before the action was called:

   add_action( 'library_loaded', 'start_my_code', 10, 2 );
   
   function start_my_code( $lib_url, $lib_directory )
   {
       # do stuff
   }
   

   The library handles all the basic parts: check for proper PHP version, WordPress constants, multi-site setups etc.

   The other code will do nothing if the action 'library_loaded' is not called.

   Log in to Reply

3. Adding to answer by chrisguitarguy, if your libraries are in the form of PHP classes, then you can utilise spl_autoload_register() to load those classes if they haven’t already been loaded by another plugin. You can then bundle the libraries into your plugin and just use them, relying on the class loader to include them when appropriate. You can also use the class loader to load your own plugin’s classes.

   e.g.

   define('WPSE_31726_PLUGIN_ROOT', dirname(__FILE__) . '/');
   
   /**
   * autoload classes as/when needed
   * @param string $class_name name of class to attempt to load
   */
   function wpse_31726_autoload($class_name) {
       static $classMap = array (
           'Wpse31726_Admin'       => 'class.Wpse31726_Admin.php',
           'Wpse31726_CsvLoader'   => 'class.Wpse31726_CsvLoader.php',
           'Wpse31726_Plugin'      => 'class.Wpse31726_Plugin.php',
           'parseCSV'              => 'lib/parsecsv/parsecsv.lib.php',
       );
   
       if (isset($classMap[$class_name])) {
           require WPSE_31726_PLUGIN_ROOT . $classMap[$class_name];
       }
   }
   
   // register function for autoloading required classes
   spl_autoload_register('wpse_31726_autoload');
   

   Log in to Reply

4. Since no official vendor directory exists, I would go for the “core” plugin that does nothing but include the library. You then make your plugins require that core plugin.

   Putting the library in one of your real plugins would require the user to have that plugin enabled even though they may never want to use its functionality. A separate core plugin seems cleaner.

   Putting it directly in wp-content looks like the worst solution.

   Log in to Reply