Files
| 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 |
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