_deprecated_file()WP 2.5.0

Marks a file as deprecated and inform when it has been used.

There is a deprecated_file_included hook that will be called that can be used to get the backtrace up to what file and function included the deprecated file.

The current behavior is to trigger a user error if WP_DEBUG is true.

This function is to be used in every file that is deprecated.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

Return

null. Nothing (null).

Usage

_deprecated_file( $file, $version, $replacement, $message );
$file(string) (required)
The file that was included.
$version(string) (required)
The version of WordPress that deprecated the file.
$replacement(string)
The file that should have been included based on ABSPATH.
Default: empty string
$message(string)
A message regarding the change.
Default: empty string

Changelog

Since 2.5.0 Introduced.
Since 5.4.0 This function is no longer marked as "private".
Since 5.4.0 The error type is now classified as E_USER_DEPRECATED (used to default to E_USER_NOTICE).

_deprecated_file() code WP 6.5.2

function _deprecated_file( $file, $version, $replacement = '', $message = '' ) {

	/**
	 * Fires when a deprecated file is called.
	 *
	 * @since 2.5.0
	 *
	 * @param string $file        The file that was called.
	 * @param string $replacement The file that should have been included based on ABSPATH.
	 * @param string $version     The version of WordPress that deprecated the file.
	 * @param string $message     A message regarding the change.
	 */
	do_action( 'deprecated_file_included', $file, $replacement, $version, $message );

	/**
	 * Filters whether to trigger an error for deprecated files.
	 *
	 * @since 2.5.0
	 *
	 * @param bool $trigger Whether to trigger the error for deprecated files. Default true.
	 */
	if ( WP_DEBUG && apply_filters( 'deprecated_file_trigger_error', true ) ) {
		$message = empty( $message ) ? '' : ' ' . $message;

		if ( function_exists( '__' ) ) {
			if ( $replacement ) {
				$message = sprintf(
					/* translators: 1: PHP file name, 2: Version number, 3: Alternative file name. */
					__( 'File %1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.' ),
					$file,
					$version,
					$replacement
				) . $message;
			} else {
				$message = sprintf(
					/* translators: 1: PHP file name, 2: Version number. */
					__( 'File %1$s is <strong>deprecated</strong> since version %2$s with no alternative available.' ),
					$file,
					$version
				) . $message;
			}
		} else {
			if ( $replacement ) {
				$message = sprintf(
					'File %1$s is <strong>deprecated</strong> since version %2$s! Use %3$s instead.',
					$file,
					$version,
					$replacement
				);
			} else {
				$message = sprintf(
					'File %1$s is <strong>deprecated</strong> since version %2$s with no alternative available.',
					$file,
					$version
				) . $message;
			}
		}

		wp_trigger_error( '', $message, E_USER_DEPRECATED );
	}
}