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The plugin API is located in this file, which allows for creating actions and filters and hooking functions, and methods. The functions or methods will then be run when the action or filter is called. The API callback examples reference functions, but can be methods of classes. To hook methods, you'll need to pass an array one of two ways.
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| add_filter( $tag, $function_to_add, $priority = 10, $accepted_args = 1 ) X-Ref |
| Hook a function or method to a specific filter action. WordPress offers filter hooks to allow plugins to modify various types of internal data at runtime. A plugin can modify data by binding a callback to a filter hook. When the filter is later applied, each bound callback is run in order of priority, and given the opportunity to modify a value by returning a new value. The following example shows how a callback function is bound to a filter hook. Note that `$example` is passed to the callback, (maybe) modified, then returned: function example_callback( $example ) { // Maybe modify $example in some way. return $example; } add_filter( 'example_filter', 'example_callback' ); Bound callbacks can accept from none to the total number of arguments passed as parameters in the corresponding apply_filters() call. In other words, if an apply_filters() call passes four total arguments, callbacks bound to it can accept none (the same as 1) of the arguments or up to four. The important part is that the `$accepted_args` value must reflect the number of arguments the bound callback *actually* opted to accept. If no arguments were accepted by the callback that is considered to be the same as accepting 1 argument. For example: // Filter call. $value = apply_filters( 'hook', $value, $arg2, $arg3 ); // Accepting zero/one arguments. function example_callback() { ... return 'some value'; } add_filter( 'hook', 'example_callback' ); // Where $priority is default 10, $accepted_args is default 1. // Accepting two arguments (three possible). function example_callback( $value, $arg2 ) { ... return $maybe_modified_value; } add_filter( 'hook', 'example_callback', 10, 2 ); // Where $priority is 10, $accepted_args is 2. *Note:* The function will return true whether or not the callback is valid. It is up to you to take care. This is done for optimization purposes, so everything is as quick as possible. param: string $tag The name of the filter to hook the $function_to_add callback to. param: callable $function_to_add The callback to be run when the filter is applied. param: int $priority Optional. Used to specify the order in which the functions param: int $accepted_args Optional. The number of arguments the function accepts. Default 1. return: true |
| has_filter( $tag, $function_to_check = false ) X-Ref |
| Check if any filter has been registered for a hook. param: string $tag The name of the filter hook. param: callable|bool $function_to_check Optional. The callback to check for. Default false. return: false|int If $function_to_check is omitted, returns boolean for whether the hook has |
| apply_filters( $tag, $value ) X-Ref |
| Calls the callback functions that have been added to a filter hook. The callback functions attached to the filter hook are invoked by calling this function. This function can be used to create a new filter hook by simply calling this function with the name of the new hook specified using the `$tag` parameter. The function also allows for multiple additional arguments to be passed to hooks. Example usage: // The filter callback function function example_callback( $string, $arg1, $arg2 ) { // (maybe) modify $string return $string; } add_filter( 'example_filter', 'example_callback', 10, 3 ); /* * Apply the filters by calling the 'example_callback()' function that's * hooked onto `example_filter` above. * * - 'example_filter' is the filter hook * - 'filter me' is the value being filtered * - $arg1 and $arg2 are the additional arguments passed to the callback. $value = apply_filters( 'example_filter', 'filter me', $arg1, $arg2 ); param: string $tag The name of the filter hook. param: mixed $value The value to filter. param: mixed ...$args Additional parameters to pass to the callback functions. return: mixed The filtered value after all hooked functions are applied to it. |
| apply_filters_ref_array( $tag, $args ) X-Ref |
| Calls the callback functions that have been added to a filter hook, specifying arguments in an array. param: string $tag The name of the filter hook. param: array $args The arguments supplied to the functions hooked to $tag. return: mixed The filtered value after all hooked functions are applied to it. |
| remove_filter( $tag, $function_to_remove, $priority = 10 ) X-Ref |
| Removes a function from a specified filter hook. This function removes a function attached to a specified filter hook. This method can be used to remove default functions attached to a specific filter hook and possibly replace them with a substitute. To remove a hook, the $function_to_remove and $priority arguments must match when the hook was added. This goes for both filters and actions. No warning will be given on removal failure. param: string $tag The filter hook to which the function to be removed is hooked. param: callable $function_to_remove The name of the function which should be removed. param: int $priority Optional. The priority of the function. Default 10. return: bool Whether the function existed before it was removed. |
| remove_all_filters( $tag, $priority = false ) X-Ref |
| Remove all of the hooks from a filter. param: string $tag The filter to remove hooks from. param: int|bool $priority Optional. The priority number to remove. Default false. return: true True when finished. |
| current_filter() X-Ref |
| Retrieve the name of the current filter or action. return: string Hook name of the current filter or action. |
| current_action() X-Ref |
| Retrieve the name of the current action. return: string Hook name of the current action. |
| doing_filter( $filter = null ) X-Ref |
| Retrieve the name of a filter currently being processed. The function current_filter() only returns the most recent filter or action being executed. did_action() returns true once the action is initially processed. This function allows detection for any filter currently being executed (despite not being the most recent filter to fire, in the case of hooks called from hook callbacks) to be verified. param: null|string $filter Optional. Filter to check. Defaults to null, which return: bool Whether the filter is currently in the stack. |
| doing_action( $action = null ) X-Ref |
| Retrieve the name of an action currently being processed. param: string|null $action Optional. Action to check. Defaults to null, which checks return: bool Whether the action is currently in the stack. |
| add_action( $tag, $function_to_add, $priority = 10, $accepted_args = 1 ) X-Ref |
| Hooks a function on to a specific action. Actions are the hooks that the WordPress core launches at specific points during execution, or when specific events occur. Plugins can specify that one or more of its PHP functions are executed at these points, using the Action API. param: string $tag The name of the action to which the $function_to_add is hooked. param: callable $function_to_add The name of the function you wish to be called. param: int $priority Optional. Used to specify the order in which the functions param: int $accepted_args Optional. The number of arguments the function accepts. Default 1. return: true Will always return true. |
| do_action( $tag, ...$arg ) X-Ref |
| Execute functions hooked on a specific action hook. This function invokes all functions attached to action hook `$tag`. It is possible to create new action hooks by simply calling this function, specifying the name of the new hook using the `$tag` parameter. You can pass extra arguments to the hooks, much like you can with `apply_filters()`. Example usage: // The action callback function function example_callback( $arg1, $arg2 ) { // (maybe) do something with the args } add_action( 'example_action', 'example_callback', 10, 2 ); /* * Trigger the actions by calling the 'example_callback()' function that's * hooked onto `example_action` above. * * - 'example_action' is the action hook * - $arg1 and $arg2 are the additional arguments passed to the callback. $value = do_action( 'example_action', $arg1, $arg2 ); param: string $tag The name of the action to be executed. param: mixed ...$arg Optional. Additional arguments which are passed on to the |
| did_action( $tag ) X-Ref |
| Retrieve the number of times an action is fired. param: string $tag The name of the action hook. return: int The number of times action hook $tag is fired. |
| do_action_ref_array( $tag, $args ) X-Ref |
| Calls the callback functions that have been added to an action hook, specifying arguments in an array. param: string $tag The name of the action to be executed. param: array $args The arguments supplied to the functions hooked to `$tag`. |
| has_action( $tag, $function_to_check = false ) X-Ref |
| Check if any action has been registered for a hook. param: string $tag The name of the action hook. param: callable|bool $function_to_check Optional. The callback to check for. Default false. return: bool|int If $function_to_check is omitted, returns boolean for whether the hook has |
| remove_action( $tag, $function_to_remove, $priority = 10 ) X-Ref |
| Removes a function from a specified action hook. This function removes a function attached to a specified action hook. This method can be used to remove default functions attached to a specific filter hook and possibly replace them with a substitute. param: string $tag The action hook to which the function to be removed is hooked. param: callable $function_to_remove The name of the function which should be removed. param: int $priority Optional. The priority of the function. Default 10. return: bool Whether the function is removed. |
| remove_all_actions( $tag, $priority = false ) X-Ref |
| Remove all of the hooks from an action. param: string $tag The action to remove hooks from. param: int|bool $priority The priority number to remove them from. Default false. return: true True when finished. |
| apply_filters_deprecated( $tag, $args, $version, $replacement = false, $message = null ) X-Ref |
| Fires functions attached to a deprecated filter hook. When a filter hook is deprecated, the apply_filters() call is replaced with apply_filters_deprecated(), which triggers a deprecation notice and then fires the original filter hook. Note: the value and extra arguments passed to the original apply_filters() call must be passed here to `$args` as an array. For example: // Old filter. return apply_filters( 'wpdocs_filter', $value, $extra_arg ); // Deprecated. return apply_filters_deprecated( 'wpdocs_filter', array( $value, $extra_arg ), '4.9.0', 'wpdocs_new_filter' ); param: string $tag The name of the filter hook. param: array $args Array of additional function arguments to be passed to apply_filters(). param: string $version The version of WordPress that deprecated the hook. param: string $replacement Optional. The hook that should have been used. Default false. param: string $message Optional. A message regarding the change. Default null. |
| do_action_deprecated( $tag, $args, $version, $replacement = false, $message = null ) X-Ref |
| Fires functions attached to a deprecated action hook. When an action hook is deprecated, the do_action() call is replaced with do_action_deprecated(), which triggers a deprecation notice and then fires the original hook. param: string $tag The name of the action hook. param: array $args Array of additional function arguments to be passed to do_action(). param: string $version The version of WordPress that deprecated the hook. param: string $replacement Optional. The hook that should have been used. param: string $message Optional. A message regarding the change. |
| plugin_basename( $file ) X-Ref |
| Gets the basename of a plugin. This method extracts the name of a plugin from its filename. param: string $file The filename of plugin. return: string The name of a plugin. |
| wp_register_plugin_realpath( $file ) X-Ref |
| Register a plugin's real path. This is used in plugin_basename() to resolve symlinked paths. param: string $file Known path to the file. return: bool Whether the path was able to be registered. |
| plugin_dir_path( $file ) X-Ref |
| Get the filesystem directory path (with trailing slash) for the plugin __FILE__ passed in. param: string $file The filename of the plugin (__FILE__). return: string the filesystem path of the directory that contains the plugin. |
| plugin_dir_url( $file ) X-Ref |
| Get the URL directory path (with trailing slash) for the plugin __FILE__ passed in. param: string $file The filename of the plugin (__FILE__). return: string the URL path of the directory that contains the plugin. |
| register_activation_hook( $file, $function ) X-Ref |
| Set the activation hook for a plugin. When a plugin is activated, the action 'activate_PLUGINNAME' hook is called. In the name of this hook, PLUGINNAME is replaced with the name of the plugin, including the optional subdirectory. For example, when the plugin is located in wp-content/plugins/sampleplugin/sample.php, then the name of this hook will become 'activate_sampleplugin/sample.php'. When the plugin consists of only one file and is (as by default) located at wp-content/plugins/sample.php the name of this hook will be 'activate_sample.php'. param: string $file The filename of the plugin including the path. param: callable $function The function hooked to the 'activate_PLUGIN' action. |
| register_deactivation_hook( $file, $function ) X-Ref |
| Set the deactivation hook for a plugin. When a plugin is deactivated, the action 'deactivate_PLUGINNAME' hook is called. In the name of this hook, PLUGINNAME is replaced with the name of the plugin, including the optional subdirectory. For example, when the plugin is located in wp-content/plugins/sampleplugin/sample.php, then the name of this hook will become 'deactivate_sampleplugin/sample.php'. When the plugin consists of only one file and is (as by default) located at wp-content/plugins/sample.php the name of this hook will be 'deactivate_sample.php'. param: string $file The filename of the plugin including the path. param: callable $function The function hooked to the 'deactivate_PLUGIN' action. |
| register_uninstall_hook( $file, $callback ) X-Ref |
| Set the uninstallation hook for a plugin. Registers the uninstall hook that will be called when the user clicks on the uninstall link that calls for the plugin to uninstall itself. The link won't be active unless the plugin hooks into the action. The plugin should not run arbitrary code outside of functions, when registering the uninstall hook. In order to run using the hook, the plugin will have to be included, which means that any code laying outside of a function will be run during the uninstallation process. The plugin should not hinder the uninstallation process. If the plugin can not be written without running code within the plugin, then the plugin should create a file named 'uninstall.php' in the base plugin folder. This file will be called, if it exists, during the uninstallation process bypassing the uninstall hook. The plugin, when using the 'uninstall.php' should always check for the 'WP_UNINSTALL_PLUGIN' constant, before executing. param: string $file Plugin file. param: callable $callback The callback to run when the hook is called. Must be |
| _wp_call_all_hook( $args ) X-Ref |
| Call the 'all' hook, which will process the functions hooked into it. The 'all' hook passes all of the arguments or parameters that were used for the hook, which this function was called for. This function is used internally for apply_filters(), do_action(), and do_action_ref_array() and is not meant to be used from outside those functions. This function does not check for the existence of the all hook, so it will fail unless the all hook exists prior to this function call. param: array $args The collected parameters from the hook that was called. |
| _wp_filter_build_unique_id( $tag, $function, $priority ) X-Ref |
| Build Unique ID for storage and retrieval. The old way to serialize the callback caused issues and this function is the solution. It works by checking for objects and creating a new property in the class to keep track of the object and new objects of the same class that need to be added. It also allows for the removal of actions and filters for objects after they change class properties. It is possible to include the property $wp_filter_id in your class and set it to "null" or a number to bypass the workaround. However this will prevent you from adding new classes and any new classes will overwrite the previous hook by the same class. Functions and static method callbacks are just returned as strings and shouldn't have any speed penalty. param: string $tag Used in counting how many hooks were applied param: callable $function Used for creating unique id param: int|bool $priority Used in counting how many hooks were applied. If === false return: string|false Unique ID for usage as array key or false if $priority === false |
| Generated: Sat Nov 23 20:47:33 2019 | Cross-referenced by PHPXref 0.7 |