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function is not described

_deprecated_hook() WP 4.6.0

Marks a deprecated action or filter hook as deprecated and throws a notice.

Use the 'deprecated_hook_run' action to get the backtrace describing where the deprecated hook was called.

Default behavior is to trigger a user error if WP_DEBUG is true.

This function is called by the do_action_deprecated() and apply_filters_deprecated() functions, and so generally does not need to be called directly.

Return

Null. Nothing.

Usage

_deprecated_hook( $hook, $version, $replacement, $message );
$hook(string) (required)
The hook that was used.
$version(string) (required)
The version of WordPress that deprecated the hook.
$replacement(string)
The hook that should have been used.
Default: null
$message(string)
A message regarding the change.
Default: null

Changelog

Since 4.6.0 Introduced.

Code of deprecated hook: wp-includes/functions.php WP 5.2.2

<?php
function _deprecated_hook( $hook, $version, $replacement = null, $message = null ) {
	/**
	 * Fires when a deprecated hook is called.
	 *
	 * @since 4.6.0
	 *
	 * @param string $hook        The hook that was called.
	 * @param string $replacement The hook that should be used as a replacement.
	 * @param string $version     The version of WordPress that deprecated the argument used.
	 * @param string $message     A message regarding the change.
	 */
	do_action( 'deprecated_hook_run', $hook, $replacement, $version, $message );

	/**
	 * Filters whether to trigger deprecated hook errors.
	 *
	 * @since 4.6.0
	 *
	 * @param bool $trigger Whether to trigger deprecated hook errors. Requires
	 *                      `WP_DEBUG` to be defined true.
	 */
	if ( WP_DEBUG && apply_filters( 'deprecated_hook_trigger_error', true ) ) {
		$message = empty( $message ) ? '' : ' ' . $message;
		if ( ! is_null( $replacement ) ) {
			/* translators: 1: WordPress hook name, 2: version number, 3: alternative hook name */
			trigger_error( sprintf( __( '%1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.' ), $hook, $version, $replacement ) . $message );
		} else {
			/* translators: 1: WordPress hook name, 2: version number */
			trigger_error( sprintf( __( '%1$s is <strong>deprecated</strong> since version %2$s with no alternative available.' ), $hook, $version ) . $message );
		}
	}
}