WordPress Hooks Explorer

Listing all hooks extracted WordPress Core

Details about example_filter

Back to home


Filename Hook Type Line Number PHP Doc
wp-includes/plugin.php apply_filters 158 /**
* Adds a callback function to a filter hook.
* 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.
* @since 0.71
* @global WP_Hook[] $wp_filter A multidimensional array of all hooks and the callbacks hooked to them.
* @param string $hook_name The name of the filter to add the callback to.
* @param callable $callback 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 filter are executed.
* Lower numbers correspond with earlier execution,
* and functions with the same priority are executed
* in the order in which they were added to the filter. Default 10.
* @param int $accepted_args Optional. The number of arguments the function accepts. Default 1.
* @return true Always returns true.

Hook Parameters

Parameter Type Name Description