/**
  * Fetches the directory object for the module with
  * the matching name.
  *
  * Each module and plug-in should store its project-specific data
  * in its own directory.
  * This function returns that directory.
  *
  * @param string $module_name The identifying name of the module.
  */
 public static function get_directory($module_name)
 {
     if (HaddockProjectOrganisation_ModuleDirectoriesHelper::insist_module_directory_exists($module_name)) {
         $project_specific_directory = HaddockProjectOrganisation_ProjectSpecificDirectoryHelper::get_project_specific_directory();
         $directory_name = $project_specific_directory->get_name() . DIRECTORY_SEPARATOR . 'data' . DIRECTORY_SEPARATOR . $module_name;
         FileSystem_DirectoryHelper::mkdir_parents($directory_name);
         return new FileSystem_Directory($directory_name);
     }
 }