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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, $accepted_args = 1) X-Ref |
| Hooks a function or method to a specific filter action. Filters are the hooks that WordPress launches to modify text of various types before adding it to the database or sending it to the browser screen. Plugins can specify that one or more of its PHP functions is executed to modify specific types of text at these times, using the Filter API. To use the API, the following code should be used to bind a callback to the filter. <code> function example_hook($example) { echo $example; } add_filter('example_filter', 'example_hook'); </code> In WordPress 1.5.1+, hooked functions can take extra arguments that are set when the matching do_action() or apply_filters() call is run. The $accepted_args allow for calling functions only when the number of args match. Hooked functions can take extra arguments that are set when the matching do_action() or apply_filters() call is run. For example, the action comment_id_not_found will pass any functions that hook onto it the ID of the requested comment. <strong>Note:</strong> the function will return true no matter if the function was hooked fails or not. There are no checks for whether the function exists beforehand and no checks to whether the <tt>$function_to_add is even a string. It is up to you to take care and this is done for optimization purposes, so everything is as quick as possible. return: boolean true param: string $tag The name of the filter to hook the $function_to_add to. param: callback $function_to_add The name of the function to be called when the filter is applied. param: int $priority optional. Used to specify the order in which the functions associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action. param: int $accepted_args optional. The number of arguments the function accept (default 1). since: 0.71 |
| has_filter($tag, $function_to_check = false) X-Ref |
| Check if any filter has been registered for a hook. return: int|boolean Optionally returns the priority on that hook for the specified function. param: string $tag The name of the filter hook. param: callback $function_to_check optional. If specified, return the priority of that function on this hook or false if not attached. since: 2.5 |
| apply_filters($tag, $value) X-Ref |
| Call the functions added to a filter hook. The callback functions attached to filter hook $tag 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 $tag parameter. The function allows for additional arguments to be added and passed to hooks. <code> function example_hook($string, $arg1, $arg2) { //Do stuff return $string; } $value = apply_filters('example_filter', 'filter me', 'arg1', 'arg2'); </code> return: mixed The filtered value after all hooked functions are applied to it. param: string $tag The name of the filter hook. param: mixed $value The value on which the filters hooked to <tt>$tag</tt> are applied on. param: mixed $var,... Additional variables passed to the functions hooked to <tt>$tag</tt>. since: 0.71 |
| apply_filters_ref_array($tag, $args) X-Ref |
| Execute functions hooked on a specific filter hook, specifying arguments in an array. return: mixed The filtered value after all hooked functions are applied to it. param: string $tag The name of the filter hook. param: array $args The arguments supplied to the functions hooked to <tt>$tag</tt> since: 3.0.0 |
| remove_filter($tag, $function_to_remove, $priority = 10, $accepted_args = 1) 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. return: boolean Whether the function existed before it was removed. param: string $tag The filter hook to which the function to be removed is hooked. param: callback $function_to_remove The name of the function which should be removed. param: int $priority optional. The priority of the function (default: 10). param: int $accepted_args optional. The number of arguments the function accpets (default: 1). since: 1.2 |
| remove_all_filters($tag, $priority = false) X-Ref |
| Remove all of the hooks from a filter. return: bool True when finished. param: string $tag The filter to remove hooks from. param: int $priority The priority number to remove. since: 2.7 |
| current_filter() X-Ref |
| Retrieve the name of the current filter or action. return: string Hook name of the current filter or action. since: 2.5 |
| add_action($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: callback $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 associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action. param: int $accepted_args optional. The number of arguments the function accept (default 1). since: 1.2 |
| do_action($tag, $arg = '') X-Ref |
| Execute functions hooked on a specific action hook. This function invokes all functions attached to action hook $tag. It is possible to create new action hooks by simply calling this function, specifying the name of the new hook using the <tt>$tag</tt> parameter. You can pass extra arguments to the hooks, much like you can with apply_filters(). return: null Will return null if $tag does not exist in $wp_filter array param: string $tag The name of the action to be executed. param: mixed $arg,... Optional additional arguments which are passed on to the functions hooked to the action. since: 1.2 |
| did_action($tag) X-Ref |
| Retrieve the number times an action is fired. return: int The number of times action hook <tt>$tag</tt> is fired param: string $tag The name of the action hook. since: 2.1 |
| do_action_ref_array($tag, $args) X-Ref |
| Execute functions hooked on a specific action hook, specifying arguments in an array. return: null Will return null if $tag does not exist in $wp_filter array param: string $tag The name of the action to be executed. param: array $args The arguments supplied to the functions hooked to <tt>$tag</tt> since: 2.1 |
| has_action($tag, $function_to_check = false) X-Ref |
| Check if any action has been registered for a hook. return: int|boolean Optionally returns the priority on that hook for the specified function. param: string $tag The name of the action hook. param: callback $function_to_check optional. If specified, return the priority of that function on this hook or false if not attached. since: 2.5 |
| remove_action($tag, $function_to_remove, $priority = 10, $accepted_args = 1) 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. return: boolean Whether the function is removed. param: string $tag The action hook to which the function to be removed is hooked. param: callback $function_to_remove The name of the function which should be removed. param: int $priority optional The priority of the function (default: 10). param: int $accepted_args optional. The number of arguments the function accpets (default: 1). since: 1.2 |
| remove_all_actions($tag, $priority = false) X-Ref |
| Remove all of the hooks from an action. return: bool True when finished. param: string $tag The action to remove hooks from. param: int $priority The priority number to remove them from. since: 2.7 |
| plugin_basename($file) X-Ref |
| Gets the basename of a plugin. This method extracts the name of a plugin from its filename. return: string The name of a plugin. param: string $file The filename of plugin. since: 1.5 |
| plugin_dir_path( $file ) X-Ref |
| Gets the filesystem directory path (with trailing slash) for the plugin __FILE__ passed in return: string the filesystem path of the directory that contains the plugin param: string $file The filename of the plugin (__FILE__) since: 2.8 |
| plugin_dir_url( $file ) X-Ref |
| Gets the URL directory path (with trailing slash) for the plugin __FILE__ passed in return: string the URL path of the directory that contains the plugin param: string $file The filename of the plugin (__FILE__) since: 2.8 |
| register_activation_hook($file, $function) X-Ref |
| Set the activation hook for a plugin. When a plugin is activated, the action 'activate_PLUGINNAME' hook is activated. 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/plugin/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/plugin/sample.php the name of this hook will be 'activate_sample.php'. param: string $file The filename of the plugin including the path. param: callback $function the function hooked to the 'activate_PLUGIN' action. since: 2.0 |
| register_deactivation_hook($file, $function) X-Ref |
| Set the deactivation hook for a plugin. When a plugin is deactivated, the action 'deactivate_PLUGINNAME' hook is deactivated. 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/plugin/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/plugin/sample.php the name of this hook will be 'activate_sample.php'. param: string $file The filename of the plugin including the path. param: callback $function the function hooked to the 'activate_PLUGIN' action. since: 2.0 |
| register_uninstall_hook($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 uninstall process. The plugin should not hinder the uninstall 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 uninstall 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 param: callback $callback The callback to run when the hook is called. since: 2.7 |
| _wp_call_all_hook($args) X-Ref |
| Calls 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. param: string $hook Optional. The hook name that was used to call the 'all' hook. since: 2.5 |
| _wp_filter_build_unique_id($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 an 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. return: string|bool Unique ID for usage as array key or false if $priority === false and $function is an object reference, and it does not already have a uniqe id. param: string $tag Used in counting how many hooks were applied param: callback $function Used for creating unique id param: int|bool $priority Used in counting how many hooks were applied. If === false and $function is an object reference, we return the unique id only if it already has one, false otherwise. param: string $type filter or action since: 2.2.3 |
| Generated: Thu Dec 26 01:01:01 2024 | Cross-referenced by PHPXref 0.7.1 |