* function example_hook($example) { echo $example; } * * add_filter('example_filter', 'example_hook'); * * * 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. * * Note: 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 $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 $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 $accepted_args optional. The number of arguments the function accept (default 1). * @return boolean true */ function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) { global $wp_filter, $merged_filters; $idx = _wp_filter_build_unique_id($tag, $function_to_add, $priority); $wp_filter[$tag][$priority][$idx] = array('function' => $function_to_add, 'accepted_args' => $accepted_args); unset( $merged_filters[ $tag ] ); return true; } /** * has_filter() - Check if any filter has been registered for a hook. * * @package WordPress * @subpackage Plugin * @since 2.5 * @global array $wp_filter Stores all of the filters * * @param string $tag The name of the filter hook. * @param callback $function_to_check optional. If specified, return the priority of that function on this hook or false if not attached. * @return int|boolean Optionally returns the priority on that hook for the specified function. */ function has_filter($tag, $function_to_check = false) { global $wp_filter; $has = !empty($wp_filter[$tag]); if ( false === $function_to_check || false == $has ) return $has; if ( !$idx = _wp_filter_build_unique_id($tag, $function_to_check, false) ) return false; foreach ( array_keys($wp_filter[$tag]) as $priority ) { if ( isset($wp_filter[$tag][$priority][$idx]) ) return $priority; } return false; } /** * apply_filters() - 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 $tag parameter. * * The function allows for additional arguments to be added and passed to hooks. * * function example_hook($string, $arg1, $arg2) * { * //Do stuff * return $string; * } * $value = apply_filters('example_filter', 'filter me', 'arg1', 'arg2'); * * * @package WordPress * @subpackage Plugin * @since 0.71 * @global array $wp_filter Stores all of the filters * @global array $merge_filters Merges the filter hooks using this function. * @global array $wp_current_filter stores the list of current filters with the current one last * * @param string $tag The name of the filter hook. * @param mixed $value The value on which the filters hooked to $tag are applied on. * @param mixed $var,... Additional variables passed to the functions hooked to $tag. * @return mixed The filtered value after all hooked functions are applied to it. */ function apply_filters($tag, $value) { global $wp_filter, $merged_filters, $wp_current_filter; $args = array(); $wp_current_filter[] = $tag; // Do 'all' actions first if ( isset($wp_filter['all']) ) { $args = func_get_args(); _wp_call_all_hook($args); } if ( !isset($wp_filter[$tag]) ) { array_pop($wp_current_filter); return $value; } // Sort if ( !isset( $merged_filters[ $tag ] ) ) { ksort($wp_filter[$tag]); $merged_filters[ $tag ] = true; } reset( $wp_filter[ $tag ] ); if ( empty($args) ) $args = func_get_args(); do { foreach( (array) current($wp_filter[$tag]) as $the_ ) if ( !is_null($the_['function']) ){ $args[1] = $value; $value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args'])); } } while ( next($wp_filter[$tag]) !== false ); array_pop( $wp_current_filter ); return $value; } /** * remove_filter() - 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. * * @package WordPress * @subpackage Plugin * @since 1.2 * * @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 $accepted_args optional. The number of arguments the function accpets (default: 1). * @return boolean Whether the function existed before it was removed. */ function remove_filter($tag, $function_to_remove, $priority = 10, $accepted_args = 1) { $function_to_remove = _wp_filter_build_unique_id($tag, $function_to_remove, $priority); $r = isset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]); if ( true === $r) { unset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]); if ( empty($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 $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 $accepted_args optional. The number of arguments the function accept (default 1). */ function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) { return add_filter($tag, $function_to_add, $priority, $accepted_args); } /** * do_action() - 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(). * * @see apply_filters() This function works similar with the exception that nothing is * returned and only the functions or methods are called. * * @package WordPress * @subpackage Plugin * @since 1.2 * @global array $wp_filter Stores all of the filters * @global array $wp_actions Increments the amount of times action was triggered. * * @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. * @return null Will return null if $tag does not exist in $wp_filter array */ function do_action($tag, $arg = '') { global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter; if ( is_array($wp_actions) ) $wp_actions[] = $tag; else $wp_actions = array($tag); $wp_current_filter[] = $tag; // Do 'all' actions first if ( isset($wp_filter['all']) ) { $all_args = func_get_args(); _wp_call_all_hook($all_args); } if ( !isset($wp_filter[$tag]) ) { array_pop($wp_current_filter); return; } $args = array(); if ( is_array($arg) && 1 == count($arg) && is_object($arg[0]) ) // array(&$this) $args[] =& $arg[0]; else $args[] = $arg; for ( $a = 2; $a < func_num_args(); $a++ ) $args[] = func_get_arg($a); // Sort if ( !isset( $merged_filters[ $tag ] ) ) { ksort($wp_filter[$tag]); $merged_filters[ $tag ] = true; } reset( $wp_filter[ $tag ] ); do { foreach ( (array) current($wp_filter[$tag]) as $the_ ) if ( !is_null($the_['function']) ) call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args'])); } while ( next($wp_filter[$tag]) !== false ); array_pop($wp_current_filter); } /** * did_action() - Return the number times an action is fired. * * @package WordPress * @subpackage Plugin * @since 2.1 * @global array $wp_actions Increments the amount of times action was triggered. * * @param string $tag The name of the action hook. * @return int The number of times action hook $tag is fired */ function did_action($tag) { global $wp_actions; if ( empty($wp_actions) ) return 0; return count(array_keys($wp_actions, $tag)); } /** * do_action_ref_array() - Execute functions hooked on a specific action hook, specifying arguments in an array. * * @see do_action() This function is identical, but the arguments passed to * the functions hooked to $tag are supplied using an array. * * @package WordPress * @subpackage Plugin * @since 2.1 * @global array $wp_filter Stores all of the filters * @global array $wp_actions Increments the amount of times action was triggered. * * @param string $tag The name of the action to be executed. * @param array $args The arguments supplied to the functions hooked to $tag * @return null Will return null if $tag does not exist in $wp_filter array */ function do_action_ref_array($tag, $args) { global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter; if ( !is_array($wp_actions) ) $wp_actions = array($tag); else $wp_actions[] = $tag; $wp_current_filter[] = $tag; // Do 'all' actions first if ( isset($wp_filter['all']) ) { $all_args = func_get_args(); _wp_call_all_hook($all_args); } if ( !isset($wp_filter[$tag]) ) { array_pop($wp_current_filter); return; } // Sort if ( !isset( $merged_filters[ $tag ] ) ) { ksort($wp_filter[$tag]); $merged_filters[ $tag ] = true; } reset( $wp_filter[ $tag ] ); do { foreach( (array) current($wp_filter[$tag]) as $the_ ) if ( !is_null($the_['function']) ) call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args'])); } while ( next($wp_filter[$tag]) !== false ); array_pop($wp_current_filter); } /** * has_action() - Check if any action has been registered for a hook. * * @package WordPress * @subpackage Plugin * @since 2.5 * @see has_filter() has_action() is an alias of has_filter(). * * @param string $tag The name of the action hook. * @param callback $function_to_check optional. If specified, return the priority of that function on this hook or false if not attached. * @return int|boolean Optionally returns the priority on that hook for the specified function. */ function has_action($tag, $function_to_check = false) { return has_filter($tag, $function_to_check); } /** * remove_action() - 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. * * @package WordPress * @subpackage Plugin * @since 1.2 * * @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 $accepted_args optional. The number of arguments the function accpets (default: 1). * @return boolean Whether the function is removed. */ function remove_action($tag, $function_to_remove, $priority = 10, $accepted_args = 1) { return remove_filter($tag, $function_to_remove, $priority, $accepted_args); } // // Functions for handling plugins. // /** * 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 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'. * * @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 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'. * * @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 $wp_filter; // If function then just skip all of the tests and not overwrite the following. if ( is_string($function) ) return $function; // Object Class Calling else if (is_object($function[0]) ) { $obj_idx = get_class($function[0]).$function[1]; if ( !isset($function[0]->wp_filter_id) ) { if ( false === $priority ) return false; $count = count((array)$wp_filter[$tag][$priority]); $function[0]->wp_filter_id = $count; $obj_idx .= $count; unset($count); } else $obj_idx .= $function[0]->wp_filter_id; return $obj_idx; } // Static Calling else if ( is_string($function[0]) ) return $function[0].$function[1]; } ?>