* }
* add_filter( 'example_filter', 'example_callback' );
*
- * Since WordPress 1.5.1, bound callbacks can take as many arguments as are
- * passed as parameters in the corresponding apply_filters() call. The `$accepted_args`
- * parameter allows for calling functions only when the number of args match.
+ * Bound callbacks can accept from none to the total number of arguments passed as parameters
+ * in the corresponding apply_filters() call.
+ *
+ * In other words, if an apply_filters() call passes four total arguments, callbacks bound to
+ * it can accept none (the same as 1) of the arguments or up to four. The important part is that
+ * the `$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.
+ * *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.
*
* @since 0.71
*
* it doesn't need to run through that process.
*
* @param string $tag The name of the filter to hook the $function_to_add callback to.
- * @param callback $function_to_add The callback to be run when the filter is applied.
+ * @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
* associated with a particular action are executed. Default 10.
* Lower numbers correspond with earlier execution,
* @global array $wp_filter Stores all of the filters.
*
* @param string $tag The name of the filter hook.
- * @param callback|bool $function_to_check Optional. The callback to check for. Default false.
+ * @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
* anything registered. When checking a specific function, the priority of that
* hook is returned, or false if the function is not attached. When using the
$args = func_get_args();
do {
- foreach( (array) current($wp_filter[$tag]) as $the_ )
+ foreach ( (array) current($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']));
reset( $wp_filter[ $tag ] );
do {
- foreach( (array) current($wp_filter[$tag]) as $the_ )
+ foreach ( (array) current($wp_filter[$tag]) as $the_ )
if ( !is_null($the_['function']) )
$args[0] = call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
* @global array $merged_filters Merges the filter hooks using this function.
*
* @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 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.
*/
* @since 1.2.0
*
* @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 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
* associated with a particular action are executed. Default 10.
* Lower numbers correspond with earlier execution,
reset( $wp_filter[ $tag ] );
do {
- foreach( (array) current($wp_filter[$tag]) as $the_ )
+ foreach ( (array) current($wp_filter[$tag]) as $the_ )
if ( !is_null($the_['function']) )
call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
* @see has_filter() has_action() is an alias of has_filter().
*
* @param string $tag The name of the action hook.
- * @param callback|bool $function_to_check Optional. The callback to check for. Default false.
+ * @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
* anything registered. When checking a specific function, the priority of that
* hook is returned, or false if the function is not attached. When using the
* @since 1.2.0
*
* @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 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.
*/
* @since 2.0.0
*
* @param string $file The filename of the plugin including the path.
- * @param callback $function The function hooked to the 'activate_PLUGIN' action.
+ * @param callable $function The function hooked to the 'activate_PLUGIN' action.
*/
function register_activation_hook($file, $function) {
$file = plugin_basename($file);
* @since 2.0.0
*
* @param string $file The filename of the plugin including the path.
- * @param callback $function The function hooked to the 'deactivate_PLUGIN' action.
+ * @param callable $function The function hooked to the 'deactivate_PLUGIN' action.
*/
function register_deactivation_hook($file, $function) {
$file = plugin_basename($file);
* @since 2.7.0
*
* @param string $file Plugin file.
- * @param callback $callback The callback to run when the hook is called. Must be
+ * @param callable $callback The callback to run when the hook is called. Must be
* a static method or function.
*/
function register_uninstall_hook( $file, $callback ) {
reset( $wp_filter['all'] );
do {
- foreach( (array) current($wp_filter['all']) as $the_ )
+ foreach ( (array) current($wp_filter['all']) as $the_ )
if ( !is_null($the_['function']) )
call_user_func_array($the_['function'], $args);
* @staticvar int $filter_id_count
*
* @param string $tag Used in counting how many hooks were applied
- * @param callback $function Used for creating unique id
+ * @param callable $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.