* Also see the {@link http://codex.wordpress.org/Plugin_API Plugin API} for more information
* and examples on how to use a lot of these functions.
*
* @package WordPress
* @subpackage Plugin
* @since 1.5
*/
/**
* add_filter() - 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 $example; }
*
* add_filter('example_filter', 'example_hook');
* </code>
*
* In WordPress 1.5.1+, hooked functions can take extra arguments that are set when
* the matching do_action() or apply_filters() call is run. The <tt>$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 <tt>do_action()</tt> or
* <tt>apply_filters()</tt> call is run. For example, the action <tt>comment_id_not_found</tt>
* 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.
*
* @package WordPress
* @subpackage Plugin
* @since 0.71
* @global array $wp_filter Stores all of the filters added in the form of
* wp_filter['tag']['array of priorities']['array of functions serialized']['array of ['array (functions, accepted_args)]']
* @global array $merged_filters Tracks the tags that need to be merged for later. If the hook is added, it doesn't need to run through that process.
*
* @param string $tag The name of the filter to hook the <tt>$function_to_add</tt> 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 $accepted_args optional. The number of arguments the function accept (default 1).
* @return boolean true
*/
function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
if ( empty($GLOBALS['wp_filter'][$tag][$priority]) )
unset($GLOBALS['wp_filter'][$tag][$priority]);
unset($GLOBALS['merged_filters'][$tag]);
}
return $r;
}
/**
* current_filter() - Return the name of the current filter or action.
*
* @package WordPress
* @subpackage Plugin
* @since 2.5
*
* @return string Hook name of the current filter or action.
*/
function current_filter() {
global $wp_current_filter;
return end( $wp_current_filter );
}
/**
* add_action() - 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.
*
* @uses add_filter() Adds an action. Parameter list and functionality are the same.
*
* @package WordPress
* @subpackage Plugin
* @since 1.2
*
* @param string $tag The name of the action to which the <tt>$function_to-add</tt> 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 $accepted_args optional. The number of arguments the function accept (default 1).
*/
function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
* plugin_basename() - Gets the basename of a plugin.
*
* This method extracts the name of a plugin from its filename.
*
* @package WordPress
* @subpackage Plugin
* @since 1.5
*
* @access private
*
* @param string $file The filename of plugin.
* @return string The name of a plugin.
* @uses WP_PLUGIN_DIR
*/
function plugin_basename($file) {
$file = str_replace('\\','/',$file); // sanitize for Win32 installs
$file = preg_replace('|/+|','/', $file); // remove any duplicate slash
$plugin_dir = str_replace('\\','/',WP_PLUGIN_DIR); // sanitize for Win32 installs
$plugin_dir = preg_replace('|/+|','/', $plugin_dir); // remove any duplicate slash
$file = preg_replace('|^' . preg_quote($plugin_dir, '|') . '/|','',$file); // get relative path from plugins dir
return $file;
}
/**
* register_activation_hook() - Hook a function on a plugin activation action hook.
*
* 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 <tt>wp-content/plugin/sampleplugin/sample.php</tt>, 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
* <tt>wp-content/plugin/sample.php</tt> the name of this hook will be
* 'activate_sample.php'.
*
* @package WordPress
* @subpackage Plugin
* @since 2.0
*
* @access private
*
* @param string $file The filename of the plugin including the path.
* @param string $function the function hooked to the 'activate_PLUGIN' action.
*/
function register_activation_hook($file, $function) {
$file = plugin_basename($file);
add_action('activate_' . $file, $function);
}
/**
* register_deactivation_hook() - Hook a function on a plugin deactivation action hook.
*
* 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 <tt>wp-content/plugin/sampleplugin/sample.php</tt>, 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
* <tt>wp-content/plugin/sample.php</tt> the name of this hook will be
* 'activate_sample.php'.
*
* @package WordPress
* @subpackage Plugin
* @since 2.0
*
* @access private
*
* @param string $file The filename of the plugin including the path.
* @param string $function the function hooked to the 'activate_PLUGIN' action.
*/
function register_deactivation_hook($file, $function) {
$file = plugin_basename($file);
add_action('deactivate_' . $file, $function);
}
/**
* _wp_call_all_hook() - 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.
*
* @package WordPress
* @subpackage Plugin
* @since 2.5
* @access private
*
* @uses $wp_filter Used to process all of the functions in the 'all' hook
*
* @param array $args The collected parameters from the hook that was called.
* @param string $hook Optional. The hook name that was used to call the 'all' hook.
*/
function _wp_call_all_hook($args) {
global $wp_filter;
reset( $wp_filter['all'] );
do {
foreach( (array) current($wp_filter['all']) as $the_ )
if ( !is_null($the_['function']) )
call_user_func_array($the_['function'], $args);
} while ( next($wp_filter['all']) !== false );
}
/**
* _wp_filter_build_unique_id() - 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.
*
* @package WordPress
* @subpackage Plugin
* @since 2.2.3
*
* @link http://trac.wordpress.org/ticket/3875
*
* @access private
*
* @global array $wp_filter Storage for all of the filters and actions
* @param string $tag Used in counting how many hooks were applied
* @param string|array $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 $type filter or action
* @return string Unique ID for usage as array key
*/
function _wp_filter_build_unique_id($tag, $function, $priority) {
global $wp_filter;
// If function then just skip all of the tests and not overwrite the following.
