The plugins_loaded Hook in WPFTS

The plugins_loaded hook is a standard WordPress hook that fires after all plugins have been loaded. WPFTS uses this hook to load the plugin’s text domain, enabling translation of the plugin’s interface into different languages. WPFTS also initializes its core classes and functions on this hook, if the plugin core is already loaded.

What WPFTS does when plugins_loaded is called:

1. Loading the text domain: Calls the wpfts_load_plugin_textdomain() function to load the plugin’s translation file. This allows using the __() function for translating interface strings.

2. Initializing the plugin core (if available): Checks if the global variable $wpfts_core exists and is an instance of the WPFTS_Core class. If so, it means the plugin core has already been loaded and initialized (e.g., through wpfts_init_addons), and the following actions are performed on this hook:

   • Calling the WPFTS_Core::set_hooks() method to register hooks related to search.
   • Registering AJAX handlers for autocomplete (wpfts_autocomplete_proc).
   • Registering AJAX handlers for forced indexing (WPFTS_Core::ajax_force_index()).
   • Adding the safe_style_css filter for supporting specific CSS.
   • Adding a handler for post_submitbox_misc_actions to display the indexing status.
   • Enqueuing admin scripts and styles if the request is from the admin panel (wpfts_admin_menu, wpfts_plugin_links, wpfts_enqueues).
   • Registering AJAX handlers for internal plugin functions (wpftsi_ping, wpftsi_set_pause, wpftsi_hide_notification, wpftsi_se_style_preview, wpftsi_se_style_reset, wpftsi_try_updatedb).
   • Registering AJAX handlers for administrator actions (wpftsi_submit_testpost, wpftsi_submit_testsearch, wpftsi_submit_rebuild, wpftsi_smartform, wpftsi_submit_upgradeindex, wpftsi_add_user_irule).
   • Calling $wpfts_core->FeatureDetector(); to detect WordPress environment specifics (e.g., to display notifications about insufficient memory limits).
   • Executing the wpfts_init_addons action to initialize add-ons.

Important functions involved in handling plugins_loaded:

• wpfts_load_plugin_textdomain()
• WPFTS_Core::set_hooks()
• WPFTS_Core::set_is_settings_page() (used in wpfts_enqueues)
• add_action() for registering AJAX handlers
• add_filter() for registering filters
• do_action('wpfts_init_addons')

How to use this in add-on development:

Add-on developers can use this hook to initialize their add-ons after all plugins have been loaded. This ensures that all necessary WordPress functions and classes are available. For integration with WPFTS, it is recommended to use the wpfts_init_addons action, which is called on the same hook.

Additional notes:

Loading the text domain on the plugins_loaded hook is standard practice for WordPress plugins, allowing for translation of the plugin’s interface into different languages. WPFTS follows this practice. It’s important to note that while much of the plugin’s logic is initialized on the plugins_loaded hook, the plugin itself begins much earlier, on the init hook, where the WPFTS_Core class instance is created.